Nothing holds the attention of visitors to a marine aquarium store more than the sight of a healthy, completely stocked, miniature reef aquarium. The variety of colors, shapes and odd-looking creatures is both bewildering and intoxicating. The gentle swaying of the coral polyps, the sparkling of light on the rocks and the darting of the fish in and out of the rock work, like so many butterflies in a field of flowers, can quickly entice the novice aquarist to purchase such a system. Yet, there is much more than meets the eye to these systems, and unless one is prepared, you can quickly become discouraged, and drop out of this branch of the hobby. Unfortunately this does not happen before hundreds, if not thousands, of dollars have been spent, and even more unfortunate, before dozens of animals have died. The secrets to having a successful reef aquarium include; having patience, gaining knowledge, exercising caution, reading everything, and practicing common sense. I also believe very strongly that you should not follow the advice of someone unless you can see what they themselves have accomplished using those methods. If you follow someone's advice you will most likely end up with what they have, so it would be a good idea to see if that is really what you would like your tank to look like.
There are so many factors to consider when setting up a reef tank that it is impossible to cover everything in a single article. Therefore I have provided a list of references at the end of this article that I encourage you to read as much of as possible BEFORE you start your aquarium. It often strikes me as strange that although most rational people will spend weeks researching and reading everything they can about a major purchase such as a car, these same people can turn around and hand over $5000 to purchase a reef aquarium setup, knowing very little about it. In my experience, most aquarists end up spending 3x as much money as they should have by fixing mistakes they made out of ignorance or by purchasing equipment/supplies they later learned they could do without.
One owes it to the animals that will eventually be put into these systems, to learn as much as you can BEFOREyou begin. Reading everything you can get your hands on will probably serve to show you that there are many different ways advocated to keep these systems, and you will become quite confused. At this point you should seek out knowledgeable people in your area who have reef systems and see what they are doing. If there is an aquarium club in your area with a marine group, then join it. If there is no aquarium club then join the specialty societies listed in many aquarium magazines. In the aquarium club I belong to, the most common comment made by new members is "I wish I had known about you people before I started!" Also, frequent the marine store in your area and get their advice. But more importantly, frequenting a marine store will expose you to other hobbyists, and it is from these people that you can also learn a great deal. Finally, no matter what advice you get, you must learn to exercise caution, a healthy dose of skepticism and common sense.
Below is given a rough outline on the costs involved in setting up a 65 gallon reef system. It is very difficult to give an accurate cost breakdown due to the wide variety of equipment and prices available. Careful comparison shopping should lower the total.
65 Gallon Aquarium $200
Having said all of the above, I would like to say that the methods I will cover in this article are based on my own experience, those of dozens of others and what I have seen in my travels across North America and Europe. I am not saying that this is the only way to do it, nor necessarily the best way, but it is what has worked for me and many others. If anyone tells you that their way is the best or only way to proceed then they are not only fooling you but themselves as well. The intent of this article will be to serve as a guide to get you started with a 65-gallon aquarium in such a way as to ensure the greatest possible chance for success, at a reasonable expense. Once you gain experience and confidence, then you can start looking for ways to change or improve your system.
1. Aquarium Selection and Placement
The first thing you must decide upon is what type of reef aquarium you want to maintain. Do you want to keep mainly soft corals or stony corals or are algae more your thing? The types of animals you choose to keep will have a great deal of influence on the type of aquarium and ancillary equipment you will need to purchase. You must realize that beginning a marine reef aquarium is a major commitment. You will be keeping animals that come to you directly from the wild. Therefore, you must be prepared to do what ever it takes to keep them in the best possible health. A reef aquarium is not something you can just set up and walk away from. Really good reef aquariums require time and nurturing to reach their full potential two or three years down the road. As a good friend of mine once wrote, only bad things happen quickly in a reef aquarium; good things happen slowly (Paletta, 1992). If you are not prepared to make this type of commitment, then this branch of the hobby is not for you.
Generally speaking, the larger the aquarium, the more forgiving it is of mistakes in water quality management. Not to say that aquariums of less than 50 gallons cannot be kept, only that one needs to be a little more vigilant that's all. A small mistake, such as a stuck heater, will have a much greater and quicker effect in a small aquarium compared to a larger aquarium. The greatest drawback to large aquariums though, is that you have to spend quite a bit of money to fill it with animals, perform water changes and it takes longer to clean.
When looking for an aquarium, beware the tall, narrow variety often available. They present numerous problems such as a poor surface area to volume ratio (very important for proper gas exchange), and difficulties in decorating and cleaning. An aquarium should at least be as deep as it is high. The standard 48"x18"x18" 65-gallon aquarium is an ideal size to begin with. It's length easily allows for the use of the most commonly available 48" fluorescent and metal halide lighting systems, and its depth and height make it easy to decorate and maintain.
Before purchasing an aquarium you should make sure that it fits in with the dimensions of the room and that the floor where it will be placed can support the weight. Placing a reef aquarium where it will receive a few hours of natural daylight is not a problem. In fact, it can be quite beneficial to the light loving invertebrates you will be keeping. As long as no overheating problems can occur, I see nothing wrong with this. The belief that natural sunlight will cause algae outbreaks is nonsense in a properly run reef tank. When choosing a site for the aquarium, keep in mind the availability of electrical outlets and a sink, both of which you will need ready access to.
2. The Basic Requirements
There are five main factors that one must keep in mind when running a reef aquarium. If these factors are not met, you will not be very successful. They are temperature, water movement, light, nutrient limitation and water chemistry.
If the temperature of your system cannot be maintained below 80F you will experience problems sooner or later. The ideal temperature range lies between 72F and 78F. How you achieve these temperatures is up to you but they must be achieved.
Water movement is extremely critical in a reef aquarium. Many of the organisms you will be keeping such as corals, cannot move from where they are growing. They depend on the water to bring them oxygen and nutrients, to take away wastes such as carbon dioxide, to remove fouling organisms and to ensure that all the polyps get enough light. This water motion can be achieved in many ways but it should not flow in a straight line (laminar flow). Best are small eddies and swirling masses of water that cause the water to flow in a chaotic manner through the aquarium. This is best achieved by having a number of water returns and/or powerheads in the aquarium, located such that their flows can interact with each other. Water motion is also critical for the suspension, and removal of detritus and debris from the aquarium. Make sure that you have good turbulence at the water surface too, as this greatly aids in gas exchange.
Light is an extremely important component in a reef aquarium. Since the majority of the corals we keep possess zooxanthellae (single celled, symbiotic dinoflagellates), they must receive both the proper intensity and spectrum of light to flourish. More will be said about lighting in a moment.
1) Check that corals etc. have no become dislodged. If corals have fallen replace immediately. 2) Check the sump level. 3) Check that skimmer is properly tuned. 4) Look for leaks in the plumbing. 5) Check the temperature. 6) Replace evaporated water with pure freshwater. This is best done through the use of a float valve attached to a reservoir.
One goal most reef aquarists strive to achieve is that of low nutrient levels in the aquarium. Namely nitrate and phosphate (since these are easily measured) plus numerous other substances generally classified as dissolved organic carbon (DOC), need to be kept at low levels. Keeping these under control is often the difference between a successful reef aquarium and an algae coated mess. Having said this I should also add that no real connection has ever been made between nitrate levels and poor coral growth. Levels as high as 40 ppm nitrogenas nitrate, have been measured in aquariums with beautiful stony coral growths (Sprung, 1992c). However, nitrate can fuel undesirable algae growth in some cases and should still be maintained as low as possible. The best way to control the levels of these wastes is through the use of protein skimming (foam fractionation) and activated carbon.
Finally, unless you can maintain proper levels of pH, alkalinity and calcium, then you will be restricted in the amount of success you will achieve in keeping and growing corals, coralline algae and clams. The field of trace elements is an extremely active area at the moment as new aquarium additives seem to appear each month. Unfortunately, how many of these products are actually the product of any original research or long-term testing is open to question. However, this is definitely an area where breakthroughs are occurring as more is learned about the requirements of corals for certain trace elements.
There has been much written concerning the filtration required to maintain a reef aquarium. Everything from pressurized trickle filters to just plain airstones has been advocated by various people over the years. Basically, filtration can be classified into three main categories: biological, mechanical and chemical. How these three are achieved is where all the variety and debate comes in. Some would have you believe that you need to purchase several hundreds of dollars worth of equipment to keep a successful aquarium.
Devices such as ozone generators, automatic water change and top-off systems, alternating surge controllers, denitrification filters, redox controllers and meters, pH meters, CO2 injectors, molecular absorption resins and trickle filters have been heavily promoted by many as absolute necessities. In my experience, while it is nice to have many of these aids, they are not necessary for success. As a corollary, having all these things on your aquarium will not guarantee success either; if you are a poor aquarist, all the technology in the world will not help you cover up that fact. I would much rather you spend your money on good quality lighting, a properly designed protein skimmer and the highest quality live rock you can afford. When these requirements have been met, then you can add other "gadgets" if you so desire.
a. Mechanical Filtration
The first component of any filtration system is the method by which water is removed from the aquarium. Here there is little argument that an overflow of one type or another is the best option. An overflow functions to continuously remove the surface layer of water, thereby increasing gas exchange and removing surface active pollutants to the filtration system. An overflow also maintains a constant level in the display aquarium.
The overflow can consist of a commercially available unit that hangs on the side of the aquarium and operates on a simple siphon. However, many hobbyists still use the drilled tank overflow where a hole is drilled either in the bottom or side of the aquarium and an overflow box built around the hole. Hang-on-the-back overflows are convenient to use and are the quickest way to retrofit an existing aquarium. Drawbacks include a low surface area for water flow, breaking of the siphon can occur, and one needs to be sure to select a pump whose flow rate the siphon can handle. Drilled overflows generally offer greater surface area for water extraction and they can not break a siphon. Drawbacks include making sure the pump is properly sized, any leaks could drain the entire tank, and the difficulty in cleaning some designs.
The mechanical removal of large particulates usually occurs in the overflow. For this reason the overflow should be easily and quickly accessible so that it can be cleaned on a regular basis. Usually some sort of untreated sponge or floss material is used to trap particles in the overflow. This prefilter, as it is called, should be cleaned or replaced on a regular basis i.e. every 2-3 days.
b. Biological Filtration
Biological filtration refers to the transformation of substances in the aquarium by many different species of bacteria. These transformations generally result in substances that can be harmful to the aquarium inhabitants. Fortunately, these substances are further acted upon by other bacteria to produce less harmful substances. Toxic by-products of waste such as ammonia, are oxidized by bacteria into less toxic nitrite, which is then further oxidized by other bacteria into least toxic nitrate. This nitrate then accumulates in the aquarium. This is, in essence, the basis of nitrification in the marine aquarium. Nitrate levels are then reduced by water changes, by assimilation by other organisms or by other biological processes such as denitrification, where yet more specialized bacteria act on the nitrate to convert it into nitrogen gas, which is quickly released from the water.
How one provides for biological filtration in a reef aquarium has come under some interesting discussion lately. Some believe that the modern trickle filter is the best way to achieve this while others, including myself, feel that in aquariums with live rock, trickle filters are not necessary for adequate biological filtration to occur. Trickle filters achieve biological filtration by presenting a favorable environment for nitrifying bacteria to grow. These bacteria then rapidly convert ammonia into nitrate, which is then returned to the aquarium. However, trickle filters do not only contain nitrifying bacteria but numerous other types that can produce still more ammonia and also phosphate. For a more in-depth discussion of trickle filters, their construction and design, I refer you to Delbeek (1990a).
Live rock consists of the calcium carbonate skeletons of long dead corals, or other calcareous organisms. Therefore the name "live rock" is really a misnomer as the rock itself is not actually "alive" but it does contain a multitude of life both inside and out. Most live rock are NOT collected from coral reefs themselves, but from adjacent areas known as a "rubble zones." These are areas where natural decay processes and storms have deposited large amounts of dead coral fragments that have become overgrown with numerous organisms. The vast majority of these pieces are eventually eroded with time or buried under sediments. These rubble areas are continuously buried, exposed and reburied by natural processes such as storms and currents, therefore any life on them is transient at best. Collection of live rock from reefs may be carried out by unscrupulous individuals and should definitely not be encouraged. Do not purchase any live rock that has sea fans and/or live stony corals attached, as these were probably illegally collected and transported.
Suggested Water Chemistry Values
The use of live rock immediately introduces into the aquarium numerous algae, bacteria and small invertebrates all of which contribute to the overall quality of the aquarium water. Live rock has just as much, if not more, surface area for bacteria than a trickle filter. Since live rock in the aquarium contains various types of bacteria, algae and corals, waste products such as ammonia, nitrate and phosphate can have a number of fates. Ammonia, nitrate and phosphate are readily assimilated by algae and photosynthetic corals growing on and in the rock. Ammonia can also be quickly converted into nitrate by the bacteria on and in the rock. This nitrate can be either absorbed by the algae and corals, or it can be denitrified by bacteria in close proximity to the nitrate-producing bacteria.
In reef aquariums that are heavily loaded with fish or where overfeeding occurs, the production of nitrate may overcome the rock's ability to handle it and you will get a build-up of nitrate in the system. This is where additional protein skimming (foam fractionation) becomes important. For more information on this topic I urge you to read Sprung and Delbeek (1990) and Sprung (1992c).
There are various methods employed today in setting up reef systems, many of which are successful; some more than others though (Sprung and Delbeek, 1990). However, I feel that the most important ingredient, the one that will ultimately determine the appearance of the system and the time taken to achieve that state, is the quality and amount of live rock used. The reason for this is that it takes time for any system to reach a balanced state and the key to achieving this balance is the condition of the live rock. The better conditioned the live rock, the more stable the system. One method used to improve the condition of fresh live rock is to let it sit in an unlit, well-filtered aquarium for at least a month (this is called "seeding" the rock). The rock is of course first stripped of all sponges and algae that could die-off and pollute the system. After about a month of seeding, the rock is placed into the intended reef tank. By seeding the rock in this way, any fouling organisms will have died off and the rock will have begun to develop significant encrusting red, pink and purple coralline algae growths. This rock is then used to build-up the basic structure of the reef. Specialized rock such as plant rock or anemone rock are not used until much latter, if at all.
Seeding the rock in this way is not always practical for the hobbyist and we are often forced to place freshly collected rock into our systems. The removal of potentially fouling organisms becomes even more important in this case as the reef tank becomes the seeding tank. The amount of time required to seed live rock depends entirely on the state the rock is in when it first arrives. In some cases there is very little die-off on the rock and the seeding period can be as short as a week. In other cases in may take much longer. Seeded rock is also commercially available. If live rock is purchased from a collector, depending on how long the rock is in transit, then some additional seeding time may still be required when it arrives. A complete description of the process of setting up a reef tank using seeded and unseeded live rock is given in Sprung and Delbeek (1990).
The source of rock is another factor that should be taken into consideration. I prefer to use "reef rock," that is, rock that has been collected from outer reef areas. These consist basically of pieces of coral and coral rock that have been broken off of the reef during a storm or through natural decay processes, and have fallen to the bottom, where they are then covered by numerous encrusting organisms such as sponges and coralline algae. To my mind this type of rock makes the most beautiful and successful reef tank. It also cycles very quickly and stabilizes the tank rapidly. Inshore rock tends to be denser and is usually covered with numerous growths of macroalgae, clams, mussels, crabs, shrimps and other unwanted organisms, in my view less desirable.
Although it is possible to start a reef tank using dead base rock and only a veneer of live rock, this takes much longer to mature and the possibility of algal outbreaks is much greater. Yet, in some aquariums, the dead base rock eventually becomes so encrusted with purple coralline algae that it is indistinguishable from live rock. In the not too distant future aquacultured live rock will be available but it will require long term experience with this type of rock before it can be determined how suitable it will be for reef aquariums.
The way the live rock is arranged in the aquarium can also have a profound influence on the long term success and maintenance of a reef tank. What one sees in many reef aquariums is a haphazard conglomeration of rock piled into a brick-like wall, with very little regard given to water circulation and detritus build-up and its removal. When arranging live rock it is much better to construct a loose arrangement of rock, with many overhangs and bridges between the rock. Try and couple this with as few contact points between the rocks, and between the rocks and the substrate as possible. Do not pile the rock up against the back of the aquarium, leave enough space behind the rock for water circulation and for detritus removal. Some aquarists suspend their live rock above the bottom of the tank with sheets of acrylic light diffusor material or feet of acrylic. This allows detritus to accumulate below the rock for easy removal by siphoning. The same effect, however, can be obtained by the judicious placement of live rock.
Of course arranging the rock in such a manner is not easy to do when most of the live rock offered for sale are smallish, rounded pieces. The ideal shape for this type of arrangement are elongated flattened pieces that can be easily arranged to form platforms and bridges. By arranging the rock in this manner, organism placement is easier, water circulates freely around the rock on all sides and detritus is quickly carried away from the rock and collects either in the prefilter or on the bottom of the tank where it can be easily removed.
The amount of live rock required in a system is difficult to assess. The general rule of thumb is to place the rock such that it takes up about 1/3 of the visual volume of the aquarium. Using estimates of mass to determine how much rock is required are crude guidelines at best. The reason for this is that live rock can vary greatly in density. To fill a 65 gallon tank 1/3 full of a dense type of rock may require 200 lbs., but if a very low density rock were used only 100 lbs. may be required.
I cannot stress enough the importance of the quality and placement of live rock in having a successful reef tank. Whether you use a trickle filter and a skimmer or only skimmers to filter your tank is irrelevant, if you have good quality rock with very little die-off, this will have a much greater affect on water quality than the filtration system. I feel that the importance of the filtering capacity of live rock has been greatly down played, and that of some filtration systems has been, perhaps, overrated.
c. Chemical Filtration
Protein Skimmers (Foam Fractionators)
The one piece of equipment I feel you should purchase is a good quality protein skimmer (foam fractionator). These devices play an extremely important role in maintaining coral reef aquariums. In my opinion, a protein skimmer is an indispensable piece of equipment for the marine aquarium, doubly so in a reef system. Foam fractionators have been in use in European aquariums for years and are often the sole form of filtration used. Obviously this cannot be achieved with the smaller, internal skimmers sold for years in North America, but by larger, external models. Such models are now commonly available in North America, the majority being North American built.
Protein skimmers consist of a column through which a very fine mixture of air and water is pumped. If any of you have been to the beach you may recall seeing foam along the shoreline. This foam is produced by the action of the waves which combine air, water and certain surface active organics to form a stable foam. A protein skimmer works in a similar manner. By collecting the foam, proteins and other nitrogen containing organics are removed before they are metabolized into nitrogenous compounds such as ammonia and nitrate, which is very beneficial to the health and maintenance of the system. Therefore there is nothing artificial or unnatural about protein skimming, it is merely the extension of a naturally occurring process. Of the various chemical filtration methods available, only protein skimming completely removes most organics before they begin to decompose (Moe, 1989). The list of substances removed by skimming includes, amino acids, protein, metals such as copper and zinc complexed with the proteins, fats, carbohydrates, phosphate, iodide, fatty acids and phenols.
Skimmers come in two popular designs, counter-current airstone driven and Venturi driven. A Venturi skimmer uses a strong water pump combined with a small air inlet to create a suction that forms a fine mixture of air and water in the skimmer. Such devices are more powerful and require less maintenance than the standard wooden airstone driven models; they can also be made smaller. Small Venturi models are more selective in what substances they will remove than counter-current designed airstone driven models. Counter-current models have an airstone at the bottom of the tube and the water flows from the top of the tube to the bottom. One of the drawbacks of these units is that they require frequent maintenance. In my opinion airstone models work quite well and remove a much thicker, darker green/brown sludge. There is no real need to purchase a more expensive Venturi design unless there are other considerations such as available space, that need to be met. The important thing to remember is that you cannot overskim an aquarium. For example the above mentioned 65 gallon could be easily run on a single 2 ft. tall, 4 in. diameter counter-current skimmer but adding another one would do no harm. For more information on protein skimmers, and instructions on how to build your own refer to Dyer and Delbeek (1991).
Bearing the above in mind, a reef aquarium can operate beautifully with or without a trickle filter but there are many variables that can affect the level of success achieved. Above all, limiting the sources and storage zones for nutrients is a general means of keeping the system operating properly whether a trickle filter is used or not. One can see, for instance, how important a piece of equipment a protein skimmer really is as a complement to the trickle filter. In removing nitrogen rich compounds before they are broken down, the protein skimmer lowers the trickle filter's potential production of nitrate. Its value is not lost in systems without a trickle filter either. This is also why most hobbyists running their aquaria with skimmers only, consider them an essential element for long-term water quality (Sprung and Delbeek, 1990).
Many of us are familiar with the use of charcoal in the old cornerbox filters of our freshwater days. These usually consisted of small, shiny, irregularly shaped pieces of bone or wood charcoal. This type of carbon is not really suitable for use in marine aquariums and has been replaced by "activated" carbon. In this form the carbon has been subjected to extremely high pressures and temperatures to drive out all impurities and gases leaving behind extremely porous and pure grains of carbon. Particle size, type of gas used, activation temperature and, in some instances, inorganic salts of zinc, copper, phosphate, silicate and sulfate added before activation, provide carbon with specific adsorption characteristics (Moe, 1989). Therefore, activated carbon can be tailored to the specific type of impurities that one wishes to remove. By creating such extremely porous structures within the carbon grains we have, in effect, created a gigantic sponge that can absorb many impurities from the passing water.
In order for this absorbtion to take place, water must flow through the carbon. Although simply placing the carbon in the sump beneath the aquarium may suffice, the most efficient use of the carbon will occur if water is actually forced to go through it. This can be achieved by placing the carbon beneath the outlet of the overflow or by using it in a separate canister filter.
One of the most common questions concerning the use of activated carbon is how much to use and how often it should be replaced. These questions are very difficult to quantify simply because no two systems are identical. Differences in bioload and the type of organisms being kept greatly influence the type and amount of DOC produced. For example, aquariums filled with macroalgae will produce a greater variety of DOCs than systems with very little algal growth. Wilkens and Birkholz (1986) recommend 500 grams per 100 liters. Although this does seem excessive one could use this as an upper figure and work downwards. The real indicator will be the condition of the inhabitants in the system and the color of the water. Too many aquarists today are turning towards technological wizardry to maintain their aquariums. People are constantly talking about ozone, redox potential and carbon dioxide systems when the majority cannot correctly identify their tank inhabitants or don't fully understand what alkalinity is. The occupants of our aquariums are far more sensitive to water chemistry than any instrument and if one spends more time watching them instead of the flashing lights on your equipment, you will be more in-tune with what is really going on in your tank.
For the same reasons mentioned above, it is difficult to recommend a specific time period after which the activated carbon should be replaced. However, various authors have stated that activated carbon should remain active for 5-7 months before needing replacement (Moe, 1989; Wilkens and Birkholz, 1986). Usually, the presence of yellowing substances in the water can be used as a guide to determining if your activated carbon needs replacing since these are easily removed by activated carbon and will start to accumulate when the carbon begins to lose its activity. Moe (1989) describes the following method. Obtain a strip of white plastic and color one half a faint yellow with a marker. Place the strip in the water and observe from a distance. When you can no longer distinguish the yellow half from the white half, your water contains yellowing substances and you should replace your activated carbon.
There are numerous brands of activated carbon being marketed today, some of which have fancy names such as research grade. Unfortunately, not all activated carbon is created equal and the levels of efficiency and quality vary greatly. The grains of activated carbon should be small, dull black in color and as dustless as possible. Recent measurements of activated carbon filtered aquarium water have shown that certain brands will actually add phosphate to the water, which is exactly what we are trying to avoid. Some activated carbons contain high levels of ash that also can contribute to undesirable algae growth. If you are unsure if your carbon brand leaches out phosphate you can rinse the activated carbon in pure freshwater thoroughly and then use it. This should remove some, but not all of the phosphate. One way to determine phosphate release by carbon is to purchase a phosphate test kit. Perform the test on purified freshwater and then add a few grains of your activated carbon to the test vial. If you see blue trails behind the falling pieces, you will know that it releases phosphate.
A final caveat concerning activated carbon is that it uncontrollably removes substances from the water, including some useful ones. Therefore, regular water changes or trace element additions (especially iodide) take on added importance when this form of chemical filtration is used for long periods or in large quantities. For example, when it comes to keeping delicate stony reef-building corals such as Acroporidae and Pocilloporidae, or soft corals such as Xenia, continuous use of activated carbon has been found to be detrimental for the reasons mentioned above (A. Nilsen, personal communication; D. Stuber, personal communication). Under intense illumination and continuous use of large quantities of activated carbon, coral bleaching and death are not unheard of. In some cases continuous use of activated carbon has led to reduced growth rates. For this reason many aquarists use activated carbon for only a few days each month, to quickly remove accumulated toxins from the aquarium.
Much has been written about the many forms and types of lighting available for use on reef aquaria. I do not want to discuss the pros and cons of all the various types as that could fill an entire book, suffice it to say, most will work fine provided you follow certain guidelines when purchasing them. First, the spectrum of light produced should not contain high amounts of red or yellow. Second, they should contain sufficient amounts of blue light. Third, they should not overheat the aquarium. Fourth, they must not emit ultraviolet light in large amounts (if they do, then the light fixture should have proper UV shielding). And fifth, they should provide adequate intensity for the depth and types of animals you will be keeping.
When dealing with fluorescent lamps, most meet the above criteria. However, beware of using so-called "plant lights" as they contain too much red in their spectrum and may promote the growth of undesirable microalgae. If you are using 8 or more lamps then you can use one such light to enhance colors if you wish, but they must not form the majority of the lighting.
The use of metal halide lighting (specifically HQI, halogen quartz iodide) has increased greatly in the last few years. Again the same criteria mentioned above apply to these bulbs. To help ensure this, the color temperature of the bulb should be over 5000 Kelvin and the color rendition index (CRI) should be over 90. These values are usually printed in the literature or ad copy of the bulb. When used properly, these bulbs give excellent results but they tend to be more expensive than fluorescents. To learn more about the pros and cons of these lamps and the theory used to develop the above guidelines see Delbeek (1990c).
As I mentioned earlier, this article is based on how I would setup a reef aquarium of 65 gallons. This type of aquarium could easily be lit by 6-8 48" 40 Watt fluorescent lamps and give excellent results with the majority of corals available. I generally recommend a 1:1 wattage ratio of blue and daylight spectrum lamps such as the Philips Actinic 03 and the Sylvania Daylight, respectively. The choice in fluorescent lamps is seemingly endless and the types you choose will ultimately be determined by their availability. Of course you can also use high output fluorescents of say 60 W if you prefer and if you use specular aluminum reflectors you will get even more usable intensity. For tanks of greater height, light intensity becomes more of a factor. Generally speaking, tanks 24" high or greater will require using high output or even very high output (VHO) fluorescent lamps or metal halide. These fluorescent lamps will require different ballasts than regular 40 W lamps, so you will need to take this into consideration when choosing or changing the lighting system.
The lighting should be set on timers so that you can ensure the proper photoperiod is maintained. Generally, 10 hours of fluorescent lighting is adequate and 4-8 hours of metal halide, supplemented with blue fluorescents, is sufficient. You could also use additional fluorescents to supply light before and after the metal halides come on. You can also set the timers so that the lights come on and go off in sequence, simulating changes in light intensity over the day.
5. Water Quality
Of course irrespective of the filtration and lighting systems, if the proper water quality cannot be maintained, the animals will not survive. Water quality is a rather amorphous term and encompasses many different things some of which we can easily measure and some we cannot. Water chemistry is one portion of water quality that must be maintained within certain limits. Generally speaking the following parameters are of concern: specific gravity, temperature, pH, alkalinity, calcium, ammonia, nitrate and phosphate.
a. Specific Gravity
Specific gravity is used to measure the relative salinity of seawater compared to distilled water. Distilled water has a specific gravity of 1.000 while seawater ranges from 1.022 to 1.030 depending on the region. The specific gravity is measured with the use of a hydrometer and should be between maintained between 1.022 and 1.025.
As was mentioned previously, maintaining a proper temperature is critical for reef aquariums. If you cannot provide the correct temperature range you will not be successful no matter what else you do. The temperature should be between 74 and 78oF for the best results. If the temperature varies a few degrees during the course of the day this is usually not a problem. The most common problem is too high a temperature, that is 80oF+. There are a number of possible solutions to this and one or all of them may be necessary. First you should ensure that the top of the tank has adequate air circulation, either by having a hanging light fixture over the aquarium or by having a well-ventilated light hood. This will aid gas exchange and evaporative cooling, and will retard heat build-up in the hood. You could also design your sump so that it is open and provides a large surface area for evaporative cooling. Evaporative cooling can be further enhanced by placing a fan over the water surface. The most expensive but effective solution is to purchase an aquarium chiller designed for saltwater use. Somewhat less expensive is to purchase an air conditioner unit for the aquarium room. This has an added benefit for the aquarist of course, which may help you convince your spouse of the extra expense!
The pH of aquarium water is a measure of the concentration of hydrogen and hydroxide ions. If the hydroxide ion is in greater abundance in a solution then the solution is said to be basic. If the hydrogen ion is more common the solution is acidic. Values of pH range from 0 to 14. If the number is less than 7 the solution is acidic, if it is greater than 7 it is basic and if it equals 7 it is neutral. Seawater is a basic solution with a pH of 8.2 to 8.4. In our aquariums, natural processes tend to lower the pH and we need to keep an eye on it. The pH is easy to measure with a saltwater pH test kit and should be maintained between 8.0 and 8.5. A sure sign that the pH is too low or high is the failure of your corals and clams to open completely.
This is a term that has caused a great deal of confusion amongst both novice and advanced hobbyists. Stated simply the alkalinity of a solution is its ability to act as a pH buffer against drops in pH. The greater the alkalinity the greater its ability to prevent rapid pH swings. Once the alkalinity is exhausted the pH can fall rapidly. Alkalinity is provided in the aquarium by various negatively charged ionic compounds (anions) such as carbonates, bicarbonates, borates and hydroxides, to name just a few. The rather confusing term carbonate hardness has also been used to describe alkalinity, but this refers only to the carbonate and bicarbonate portions of alkalinity and does not take into consideration the other compounds involved. Therefore alkalinity is generally slightly higher than carbonate hardness (Spotte, 1979).
To further add to the confusion, there are two different units of measurement used. There are numerous test kits available and they are all simple to use. Some test kits for alkalinity use the metric unit of milliequivalents per litter (meq/L), while other kits use the German unit, degrees of carbonate (German = karbonat) hardness (dKH). To convert meq/L to dKH simply multiply by 2.8. Natural seawater has an alkalinity of 2.1 to 2.5 (6-7 dKH). Alkalinity values in the aquarium should be maintained between 2.5 and 3.5 meq/L (7-10 dKH) through the use of commercial buffers. These buffers should also be used to maintain pH. There a numerous powdered buffers available that will maintain both alkalinity and pH, and the majority work very well by raising the alkalinity without causing rapid changes in pH. Beware of any buffers that cause rapid changes in pH.
Calcium is the primary building block of the corals, clams, calcareous algae and many other organisms that we would like to grow in our aquariums. Without adequate supplies of calcium these organisms will not flourish and most will eventually waste away and die. Calcium levels are measured in parts per million (ppm) or milligrams per litter (mg/L). Calcium levels in natural seawater range from 380 to 480 mg/L depending in location. In our aquariums calcium levels should be maintained between 380 and 450 mg/L to ensure proper growth and longevity of our animals.
How one obtains these levels is a matter of choice and debate. Some advocate the use of powdered calcium chloride while others recommend powdered calcium hydroxide. There are also numerous calcium supplements on the market with wondrous claims as to their efficiency. It remains to be seen how well these products will perform over long-term use.
Calcium chloride is easy to use and does not directly affect the pH of the aquarium. The danger in its use is that one can easily overdose and quickly raise the calcium ion level in the aquarium. This has two effects. It raises the specific gravity rapidly and it can cause a rapid drop in alkalinity, and subsequently, pH. Calcium chloride can be added directly to the sump as a powder but it is best to dissolve it first in freshwater and slowly drip it into the aquarium.
Calcium hydroxide is messy to use, has a high pH that can be hazardous as it can rapidly raise the pH if it is added too quickly, and it is caustic. It does add calcium slowly to the aquarium and does not deplete alkalinity. Generally sold as a powder, it is added to freshwater at the rate of 1 teaspoon per gallon (1.5 grams per litter). This solution, commonly called kalkwasser (German for calcium water) is then shaken and allowed to settle. The clear liquid that results is then slowly added to the aquarium as make-up water for evaporation. This is best done using a float valve or dosing pump. For more details on calcium additions see Sprung and Delbeek (1990) and Sprung (1991).
Calcium ion concentration can be easily measured using available calcium hardness test kits from chemical supply companies such as Hach and LaMotte, or your local pet store.
One last note concerning calcium. If you have access to freshwater that is low in organics, nitrates and phosphates, and is high in minerals such as calcium and magnesium, then you may not require the use of calcium supplements if you use this water for evaporation replacement.
f. Ammonia and Nitrate
Normally, ammonia levels in the aquarium should be zero. If you can measure detectable ammonia, your aquarium has either not yet cycled completely or you something is decaying in the aquarium. If the former is true, you should wait until the level drops or if you have animals that are suffering you can use one of the commercially available ammonia neutralizers. In the case of the latter, you should carefully and completely inspect your aquarium for any decaying animals, food or live rock, and remove it immediately. Organically decaying live rock is easily recognized by the smell and the white slime that usually accompanies it.
Nitrate has often been implicated as a causative agent for failure in reef aquariums. However, if the truth be known, there has never been any conclusive evidence for this. As mentioned above, nitrate levels of 40 ppm have been measured in aquaria with large stony coral growths. It would safe to say that maintaining a low level of nitrate is still desirable, but one need not become fanatical about it. Where nitrate could still pose a problem though, is in undesirable algae growth.
Phosphates can cause problems in marine aquaria, especially reef aquaria if they are allowed to build to levels above 0.2 ppm. Elevated phosphate levels will fuel unwanted algae growth and interfere with the calcification processes of corals and coralline algae. Phosphates are present in many forms in the aquarium, not all of which can be easily measured. The real trick with maintaining low phosphate levels is to minimize their input and maximize their removal.
Minimizing input relates directly to the quality of the freshwater you are using for evaporative top-offs. This water should be as free of phosphate and nitrate as possible. If you are using this water to make kalkwasser then the high pH of this solution will result in the rapid precipitation of any remaining phosphate, in the form of calcium phosphate. Beware also of any additives and salt mixes that may contain unacceptable levels of phosphate. Avoid using any liquid food supplements that may contain phosphate and check your activated carbon to make sure it does not release phosphates.
Although some have advocated minimal feedings of the fish in a reef tank, this is not always a wise practice. Unless adequate food is available, the fish will slowly waste away. Careful, moderate, but frequent feedings of high quality foods, should be carried out several times a week, if not daily. Some more active fish such asPseudanthias spp. require small feedings several times a day to maintain their health. Tangs and surgeon fish do not usually get enough vegetable matter to eat in a reef tank and these fish should be provided with a constant supply of vegetables such as leaf lettuce, bok choy, zucchini or seaweeds used for sushi such as nori.
To maximize the output of phosphate the use of adequate protein skimming is essential. Also the frequent (every 2-3 days) cleaning or replacing of the prefilter is a must. In aquariums with poor water flow, the regular removal of detritus from beneath and between the rocks should be a part of your monthly routine.
6. Trace Elements
The topic of trace elements has become quite popular again in the last few years. As a rule, very little is known about what elements corals require to grow and survive. At this point it is safe to say that strontium is a very important element in the growth of many calcareous organisms. Strontium supplements can now be purchased in almost any marine reef aquarium store. Iodide appears to be another important trace element for corals, clams and crustaceans. Again, potassium iodide and other iodide sources are readily available for purchase. At the time of this writing, there is no substantial evidence for the importance of any other elements. That is not to say that in the future the importance of others will not come to light, but for now, these two are the only ones I can definitely say in my experience, are necessary for optimum growth.
7. Aquarium Design and Set-Up
Although there are many ways to set-up a reef aquarium, I tend to favor a very simplistic approach. You may wish to follow my example or make the modifications I will include as options.
At this point I assume that you have already chosen the size, shape and location of your aquarium. Also you have decided upon, and installed, the type of overflow and lighting system you will be using. Now comes the next major decision. Do you go with protein skimmers only or will you be using a trickle filter in combination with a skimmer? Most aquarists feel more comfortable with the latter. Using a trickle filter gives you several options later on. First of all, once the tank is up and running well, you have the option of removing the biological media if you so desire. Secondly, the trickle filter gives you a ready made (albeit expensive) sump that you can use for activated carbon, float valves and any other additions you might like to make.
If you will be using a trickle filter it is best to cycle the filter separately. This is best done by directing the output of the filter directly back into the overflow, by-passing the tank. This will allow you to prepare the bacterial bed in the filter without having to fill the main tank. One then adds one of the commercially available ammonium chloride solutions to the filter and a bacterial culture, either bottled or through the addition of a cupful of gravel from an established aquarium. Once you can no longer measure any ammonia, the filter will be ready. This will usually take about 4 weeks. Empty the filter of all water and refill with new seawater. This removes any nitrate and nitrite that may have accumulated. Also at this time you can check for any leaky valves or fittings and reseal them. While you are waiting for the filter to cycle you can order your live rock and fill the aquarium with pure freshwater, either distilled, reverse osmosis or deionized. Then add the salt mix and a few powerheads to circulate everything.
I prefer making a simple sump without a trickle filter, out of a 15 or 20 gallon aquarium from which I can pump water to my skimmer and back to the tank. You can then modify this sump tank any way you like. If you can plumb the water flow coming from the aquarium so that it passes into the skimmer first, this will give you the most efficient design, however, it makes it difficult to control the flow rate through the skimmer. Otherwise, simply let the water flow into the sump and then pump it back to the aquarium. If your skimmer is tall enough, you can pump the water into the skimmer and then let it flow directly back into the tank from the skimmer. Or you can pump some water from the sump into the skimmer and return the rest directly to the aquarium. The water from the skimmer would then simply return to the sump to be recycled. I prefer to use two water pumps. One to pump the water from the sump to the skimmer and then back to the sump, and one to pump water from the sump directly to the aquarium. This way I can easily adjust the flow of water through the skimmer without affecting the water flow to the aquarium and visa versa.
Just a brief word about the types of valves included with most commercial skimmers. To control water flow most people use ball valves. These valves are great as a on-off control of water flow but are very difficult to use for fine adjustments in flow rate. The best valves to use for this are gate valves. While more expensive, they are infinitely better than ball valves when it comes to making fine adjustments in water flow, and I strongly urge that you use them on your skimmer inlet. You will save yourself a lot of headaches.
Some have argued that they do not want a 2' or 4' skimmer sitting in their living room. There are several ways around this problem, limited only by your ingenuity. If the stand was designed tall enough, you should be able to easily place two 2' skimmers underneath it. You can also design the stand and canopy so that one end of the tank is enclosed and a 4' skimmer rises within the enclosure. Other options include using screens, building the filtration system into an adjacent closet or wardrobe cupboard, or even placing it in another room or basement and running water lines through holes in the wall or floor to the tank. I have seen all of these options and they work very nicely. There is no need to have unsightly filtration equipment out in the open, all it takes is some imagination.
Once your aquarium is completely set-up and running you can add the live rock and whatever material you have chosen for the bottom. Most reef aquarists choose not to use any bottom substrate. This makes it much easier to keep the aquarium clean and allow adequate water flow around the rocks. Once your soft corals and coralline algae begin to grow, you will not see much of the bottom anyway. It is possible to have a substrate but it is much easier to run a reef tank without one.
The live rock should be prepared and arranged as described above and then added to the aquarium. Once the rock has been introduced keep the lights off for at least two weeks. This will retard the immediate growth of any microalgae as a consequence of excess nutrients being produced by any die-off of organisms such as sponges on and in the rock. Continue to monitor ammonia levels during this period. If ammonia levels become undetectable at the end of these two weeks then you can proceed on to the next step. If ammonia levels remain high then you must wait until they drop. Although there all kinds of elixirs that can be used to neutralize ammonia, I prefer to let nature take its course, what's the rush? During this period you should also check your pH, specific gravity, alkalinity and calcium levels and make adjustments as required.
Once the tank has cycled and the rock looks clean and fresh i.e. no white slime on it, then you can turn on the lights and start adding organisms. The key during the whole start-up process though is PATIENCE! Don't rush at this point and add all sorts of specimens or else you will be disappointed later!
The first things to add should be your "maintenance crew" that is the scavengers: algae and detritus eaters. These organisms are especially important if you use a substrate, i.e. they will help to keep it clean and turned over. Under this category are brittle seastars and detrital feeding sea cucumbers (not Sea Apples!) that can be easily recognized as they have oral tentacles designed for sweeping over the rocks and substrate as they crawl over the substrate. Herbivorous snails should also be among the first additions. Species such as Astrea tecta are especially desirable. Larger snail species tend to bulldoze their way over rocks and corals, often displacing pieces. Start off with as many as one snail per 2-4 gallons of water. I would also recommend that at this point you add your first fish which should be one of the tang species, preferably the Yellow Tang (Zebrasoma flavescens) and/ or the Kole Tang, Ctenochaetus striatus, to help control the growth of undesirable algae.
You may have noticed that I have not recommended adding any sea urchins. There are a couple of reasons for this. First of all urchins tend to be bulldozers and can tear down a reef tank faster than you can set it up again! Furthermore, some species of urchins actually grind away at rock and burrow into it during the day. This tends to diminish your live rock supply and creates quite a bit of detritus in the process. Many species will attempt to camouflage themselves with whatever is lying around the tank, including your, previously, well-attached soft corals. Finally, urchins tend to scrape live rock right down to the limestone, which means they will remove all those nice coralline algae you paid for and have been lovingly cultivating for months.
7. The Addition of Corals and Fish
At this point you can begin to add corals. A tank filled with soft corals is probably amongst the easiest to keep for a beginner. What usually happens, however, is that the beginner falls victim to impulse buying and ends up buying every stony coral in sight. Try to avoid this impulse and do not be swayed by a retailer who carries mainly stony corals. Hard corals should be among the last additions to your tank, if at all. What follows is a brief listing of soft corals that would make good first additions.
Mushroom Anemones (Family Actinodisciidae)
Various species are available in a variety of colors and forms. Some forms do well in lower light areas of the tank (i.e. brown varieties) while others require more light (blue varieties). In general, they require gentle current flows, not strong and do not need to be fed. Keep them away from stony corals as they tend to damage them quite easily. See Delbeek (1987) for more detailed information on keeping mushroom anemones.
Star Polyps (Family Clavulariidae)
These soft corals come in a variety of colors ranging from brown to iridescent green. They do well in medium to strong light and if given a strong current, will rapidly spread over rocks and glass. No feeding is required. These corals can be easily propagated by cutting off small pieces and placing them in other areas of the tank. If you have no substrate try placing some sections of star polyp on the bottom of the tank. They should spread out over the glass making a nice "lawn" of soft coral.
There are many different species of corals that fall under the category of "Leather" corals. Most belong to the genera Sarcophyton, Lobophytum and Sinularia. Generally speaking they do well in moderate to strong lighting, and require a good current with frequent strong bursts. No feeding is required. Be careful when placing them in the tank as some varieties can sting other corals badly. These corals can be easily propagated by cutting off small sections with sharp scissors and fastening the cuttings to a rock with thread or elastics.
Colt Corals (Cladiella spp.)
These soft corals include the common Colt Coral as well as a number of other varieties. They do quite well in medium to strong lighting with a moderate current. No feeding required. Can be propagated by gradual pinching off of branch tips.
Other Soft Corals
There are a variety of other soft corals, most of which are very easy to keep such as zoanthids (Button Polyps), which come in numerous colors and shapes. They form colonies on live rock and spread as an encrusting growth. They require moderate to strong light and some genera such as Palythoa spp. will feed. Another common soft coral is Anthelia spp. These have large polyps with long stalks (6 inches). They grow as an encrusting mat and require moderate to strong lighting and moderate current. Closely related to Anthelia is the genus Xenia. There are many species of Xenia available some which rhythmically pulsate their polyps. Xenia tend to be rather delicate and are not recommended for the beginner. Sometimes seen for sale is Clavularia spp., commonly called Glove Polyps. These are large polyps some iridescent green in color, that have a feathery appearance to them. They require a moderate, to and fro current and do not need to be fed.
The majority of Caribbean gorgonians are photosynthetic and are therefore easy to keep without direct feeding unlike their Pacific cousins that are not photosynthetic. Most have brown, blue or purple stems, some are yellow, and all have brown polyps. The thicker branched varieties are the easiest to keep. Some forms will grow very quickly (inches per month) while others grow more slowly. They can be easily propagated through cuttings and can be given supplementary feedings with live baby brine or adult brine shrimp. I have also fed them successfully with live black worms. Not all species will feed and it is not mandatory to feed photosynthetic gorgonians. Specimens belonging to the genera Pseudoplexaura, Pterogorgia, Pseudopterogorgia, Eunicea and Muricea are all easily maintained. Gorgonians require moderate current with the occasional strong burst and medium to strong lighting. Many photosynthetic gorgonians are sensitive to ultraviolet light. If your specimens do not open after a period of time try placing a piece of UV-absorbing material under your light source such as glass or Plexiglas; the recovery is often dramatic. If there are bare portions of the skeleton showing, these can regrow very quickly provided the specimen is healthy and no microalgae is growing on it. Sometimes there are numerous bare spots, especially at the tips, when a specimen first arrives from the collector. If you take a pair of scissors and cut these bare areas off, as close to the living tissue as possible, the ends will quickly (within a day) seal over and no algae can invade the colony.
If, after 6-12 months, your tank is doing well and you have no microalgae problems then you can try some stony (hard) corals. However, I hesitate to recommend them to beginners and you can have a very nice and interesting tank without them. If you can concentrate on soft corals you should have a very stable tank that will grow quite nicely. Eventually you can propagate many of the soft corals from cuttings and trade them for other species you may not have.
If you would like to try keeping some stony corals, the following is a listing of the common stony corals offered for sale. First, however, there are a few points you should make note of before you purchase a specimen. Number one is to make sure that there are no bare areas on the coral skeleton. These areas may recover but more often than not, they only become substrate for microalgae. Once microalgae takes hold you can pretty well say goodbye to that particular piece; eventually the algae will spread and destroy the rest of the coral. It is possible for such a piece to heal but this requires that no microalgae be present in your tank and that none has begun to grow on the damaged areas. Secondly, check to see that the tissue of the coral extends well over the edges and down the sides of the skeleton. This is not always easy to see, as the polyp(s) may be so large that they obscure the skeleton underneath e.g. Euphyllia and Catalaphyllia corals. Usually, if all other conditions are optimum (i.e. calcium levels are over 420 mg/L and adequate lighting) the coral should regrow these areas without too much difficulty. The exception is when microalgae has impregnated the skeleton already. Ask the salesperson to gently agitate the piece so that the polyp begins to retract, this will give you a good view of the skeleton and the associated tissue.
The easiest to keep stony corals are Plerogyra sinuosa (Bubble Coral), the Euphyllia spp. corals (i.e. Hammer Coral E. ancora and Octobubble coral, E. divisa, are the two hardiest) and Catalaphyllia (Elegans coral). Several of the so-called open brain corals (Trachyphyllia) are quite hardy as are the Turbinaria (Chalice/Plate) corals andCynaria corals (Meat Polyp). Most require only moderate lighting to do well, while Turbinaria does best under stronger lighting. They will also accept feedings of shrimp and clam but these should be kept to a minimum (e.g. once every two weeks to a month), if at all. For stony corals to do well you should maintain a calcium ion level of at least 420 mg/L, there should be NO microalgae present in the aquarium and a strontium solution should be added weekly. These corals do well in gentle to medium currents. The Euphyllia and Catalaphyllia do enjoy the occasional strong burst of current. Plerogyra, Euphyllia and Catalaphyllia corals are capable of strongly stinging other corals. Make sure they are placed far enough away from other corals such that their long "sweeper" tentacles can not touch them (see Ates 1989, Delbeek 1990d and Paletta 1990 for detailed discussions on coral aggression).
I definitely recommend that you DO NOT PURCHASE Goniopora (Flower Pot coral, Sunflower coral, etc.). This coral has RARELY been kept alive for extended times ( > 18 months) in aquariums. The only reason that stores still sell this species is because it DOES sell. If we all stop buying them then they will not be imported and these beautiful corals can remain in the ocean where they belong. Your goal should be to keep stony corals for years. To simply keep replacing corals just because they look "pretty" is not acceptable. Hobbyists must get away from the attitude that losses are acceptable and can be easily replaced. When it comes to marine organisms, losses are NOT acceptable for various ethical reasons but also because these are not domestically grown species, they are taken directly from coral reefs.
When adding stony corals to an aquarium it is often best to place them lower in the tank. This will avoid adverse reactions to strong light. Over a period of a few weeks you can begin to move the piece higher, until it reaches a point where it looks the best. The same applies to soft corals but sometimes, if you leave the piece too long in one spot, it will begin to attach to the rock and you will have a tough time removing it.
I feel that the longer you can hold off the addition of fish (other than herbivores) the better the microfauna (copepods, amphipods, mysids) in the tank will develop. What follows is a list of fish families that do well.
Most damsels do well in a reef tank but I tend to stay away from them since, in my opinion, they are too aggressive and most lose their colors as they grow. When I look at an aquarium I want to get a feeling of peace and serenity. Watching a bunch of damsels zip around the tank, chasing and nipping each other does not meet that goal. One or two damsels of different species can be manageable as long as they are varieties which stay relatively small and hold their color into adulthood such as Chrysiptera spp. and Chromis spp. There are a few genera of damsels that eat only corals and these should be avoided e.g. Paraglyphidodon spp., especially P. melas which feeds on soft corals and is commonly seen for sale, and Plectroglyphidodon spp. (Carlson, 1987).
Again, in my opinion, many clown species are not suited to reef tanks because, if they feel at home and setup residence in an anemone, they can become very territorial, especially if they start egglaying. However, the Common Clown, Amphiprion ocellaris, is one of the more docile species and does quite well. Mixing several species of clowns in one tank often leads to territorial squabbles and should be watched closely.
Although there are many different species of blennies only a few of them are commonly seen for sale. The Red Lipped Blenny (Ophioblennius atlanticus) is often imported from the Caribbean but I find them much too aggressive and in nature it has been shown that they are extremely territorial too. The Bicolour blenny (Ecsenius bicolor) is the other common blenny seen in stores. As with most blennies, they are microalgae feeders but they are not adverse to nipping at coral polyps and Tridacna clams. This may be a reflection of a lack of other suitable food stuffs in the tank but nevertheless, they will nip off polyps. There are some blennie species (e.g. Exallias brevis) that eat ONLY hard coral polyps and these should not be purchased by anyone.
Dottybacks are quite common in retail outlets and most are suitable for reef tanks. One per tank is the usual rule, unless you are prepared to lose several before you get a stable population of them. Some of them can become very aggressive as they get larger (max. 10 cm). These should be amongst the last fish added so that they will not pick on new additions to the tank. For further information on suitable types see Delbeek (1991) and Michael (1990a and b).
Angels and Pygmy Angels
Most pygmy angel species are suitable but there is a great deal of individuality within a species, some may bother corals and macroalgae, and some won't. The Coral Beauty, Centropyge bispinosus, is a hardy and commonly available Pygmy Angel that usually does quite well with corals.
Larger angelfish are similar to pygmy angels in that they tend to be individualistic. This basically means you take your coral's lives into your own hands when you add one! I have seen Regal Angels Pygoplites diacanthus, Blue-Faced Angels, Pomacanthus xanthoetapon and Navarchus Angels, P. navarchus do quite well in reef tanks but I have also heard reports of them decimating coral populations. Large angels are best left to those with more experience.
Just about ALL gobies are suitable and will do very well. Particularly desirable are the so-called Watchman Gobies belonging to the genus Amblyeleotris spp. and Cryptocentrus spp., and the Sleeper Gobies,Valenciennea spp. These fish will help keep your substrate clean and will keep detritus in suspension for easy removal by your overflow.
The common belief is that butterfly fish cannot be put in reef tanks. This is true for most species but there are some exceptions and both Longnose, Forcipiger flavissimus and Copperband (Chelmon rostratus, butterflies have been kept successfully with corals. The only losses were with small fanworms that one usually finds growing in perfusion in older tanks. The Banner fish, Heniochus acuminatus, may also be suitable but they should be watched closely (Carlson, 1987). The Pyramid Butterfly, Hemitaurichthys polylepis, is a planktivore and can also be safely kept in reef tanks.
Tangs and Surgeonfish
There are a wide variety of tangs and surgeonfish that can be easily kept in reef tanks as long as they are not larger growing species. Desirable species include any from the Zebrasoma and Ctenochaetus genera. Those of the Acanthurus genus tend to be more difficult to keep, grow fairly large and can be very aggressive.
The Mandarin, Psychedelic Fish and Scooter Fish are amongst the common dragonettes available. They either do very well or waste away. This seems to be a reflection of collecting practices and lack of nutrition. They rarely accept prepared foods and seem to do well enough feeding on the organisms found on live rock. Purchase only those specimens that have nice full, round bellies.
For further suitable fish types for reef tanks see Delbeek (1991) and Debelius (1986).
Fish to Avoid
Triggerfish have no place in a reef tank because they tend to be rather destructive. They like to rearrange and crush rocks and corals with their teeth. Large puffers such as the Arothron genus feed exclusively on live corals. The majority of the lionfish family grow too large and their mouth is always hungry! Any of the coral eating butterfly fish family are definitely no-nos such as the Raccoon Butterfly (Chaetodon lunula).
Before buying any fish check with your retailer as to their suitability in a reef tank AND check as many reference books as you can, find out what they say about the natural diet of the fish in question. Finally, a good source of objective information is your local fish club. There are many saltwater clubs in North America now and most freshwater clubs have members who are also saltwater hobbyists.