Getting Started in Reefkeeping, Part 2

Water Quality

One of the great breakthroughs in the keeping of marine organisms came when a better understanding of the nitrogen cycle came about almost 30 years ago. Prior to that saltwater systems were just looked at as being similar to freshwater systems except salt was added to the water. This fallacious reasoning caused hobbyists to start their tanks as they would a freshwater tank and as a result any new fish they added to the system would initially die. This death of fish added to a new tank came to be called "New Tank Syndrome". Fortunately eventually it was realized that what was actually killing the fish was the ammonia that was being produced by the fish themselves, which was much more toxic in the high pH environment of a saltwater system. Over time through trial and error it was determined that if hardy fish were introduced slowly and they survived the initial high levels of ammonia, eventually a population of bacteria would become established that would convert this toxic form of ammonia into less toxic nitrite and eventually nitrate. This need for a good bacterial bed led to the use of undergravel filters, which were a cheap and easy method for establishing a biological bed. Unfortunately over time these filters clog or become filled with detritus underneath their plate and as a result a tank using them needs to be completely broken down. Approximately 15 years ago the concept of live rock was introduced as a locus for biological filtration. Live rock is not rock at all, but is the remains of dead coral skeletons that have become mineralized over time. These rocks provide a perfect surface for the bacteria that convert ammonia into nitrate. The use of live rock also eliminates the need for undergravel filters as well as fish to establish the bacterial bed.

All live rock is harvested from the ocean and shipped moist to the dealer. It is shipped this way to reduce the large freight cost that would occur if it were shipped in water. In this state it is "uncured" or "fresh". As a result of this moist shipping method many of the organisms present on the rock die off and as a result release a lot of organics into the water. Once this die off has ceased and the organisms and bacteria have become stabilized this rock is considered cured. Even though the rock may be cured in a wholesale facility, the stress of shipping it causes some die off so it will need to be cured again once it reaches its final destination.

The curing of the live rock is not too difficult and as long as adequate time is allowed for this process. A general method of curing has been established over the past ten years that works quite well. Upon arrival, the rock should be rinsed in a saltwater bath of appropriate salinity and temperature. This is done in order to remove any detritus that has settled on it as well as to remove any grossly dead organisms. Upon completion of the rinse it should be inspected and any dead or unwanted organisms (bristle worms, algae, chicken liver sponge, etc.) should be removed with forceps or tweezers. Dead organisms are usually readily apparent by their white color or limp structure or by their offensive smell. Any sponges that are growing on the rock need to be removed as these cause the most fouling during the curing process. This is necessary as sponges that are exposed to air for any length of time usually die as a result of not having a means for removing air that has gotten trapped in their tissues. Also sponges tend to die slowly, so while they may appear alive on the rock, they are in the process of dying and could therefore release organics into the water for an extended period of time. All of the macroalgae should also be plucked from the rock as well. Not only will most of the algae die from the trip, releasing nutrients, but what is left will grow profusely due to the excess of nutrients present in a new tank.

After all the undesirable components have been removed, the rock should be placed in the aquarium that will eventually be its home. It should be placed close to the pattern that it will eventually rest in with the rock oriented to the light in the same manner it was in the ocean. The upper and lower surfaces of the rock are usually readily apparent and the positioning of the live rock should take this into account. The water should have been in the tank for a week or longer prior to the addition of the live rock in order to reduce as much as possible the caustic nature of freshly prepared seawater. All of the rock should be cured at once as it is very deleterious to an established reef tank to add new rock to it. The curing of the rock usually takes from 2-6 weeks depending on how much die off occurred during shipping.

While the rock is curing several things need to be done. First strong water movement on the rock is essential. By providing strong water movement any material that dies will be blown off the rock. In addition strong water movement will prevent detritus from settling on the rock and killing whatever is underneath it. To produce this water movement multiple powerheads are necessary. To augment the water movement it is often necessary to use a bulb baster to remove some of the white film that invariably forms on some of the live rock. The second factor that is important for proper curing of the live rock is good protein skimming. Using good protein skimming aids in curing the live rock in that much of the dead material is skimmed away prior to it polluting the tank. In addition the skimmer should help in adding oxygen to the water so that anaerobic conditions don't develop. During the curing regular water changes with aged saltwater should be done on a regular basis. This may be every other day during the first week and then weekly or bi-weekly once the curing has progressed. In addition to the smell subsiding after the first week the progress of the curing can be assessed by t3esting the ammonia, nitrite and nitrate levels of the tank. During the fist few days the ammonia levels may be off the scale with little or no nitrite or nitrate being present. After a week or so the ammonia levels should fall and nitrite and nitrate should rise. Curing is done when there is no longer any smell or visible dead matter on the live rock and the ammonia and nitrite levels are zero and the nitrate level is high. At this point a 25% water change should be undertaken and once it is done fish and invertebrates can be added. That is literally how simple it is to establish a biological filter for a reef tank.

Protein skimming is the other component along with live rock that has dramatically improved the success rate of the hobby by providing a better means of removing waste and thus providing clean water for corals and fish that come from water that is almost devoid of nutrients. Protein skimming utilizes the hydrophilic (water loving) and hydrophobic (water hating) aspects of various compounds in saltwater to remove unwanted compounds from the marine tank. There are several types of skimmers on the market including counter-current, venturi, downdraft and hybrids of these various methods. Regardless of which type of skimmer is employed they all work by producing air bubbles and having the water from the tank come into contact with these bubbles. When these bubbles come into contact with saltwater, electrochemical factors come into play that cause surface active compounds to adhere to these bubbles and be removed in the foam. These compounds not only include proteins and amino acids but also include molecules containing copper, magnesium, calcium and manganese as well as detritus, phenols, microalgae and plankton (Wilkens, 1973). A properly functioning skimmer will remove much of the waste from the water before it is broken down by the bacteria on the live rock. By having a good protein skimmer and adequate live rock the water quality of a reef tank can be maintained a high level without the need for much other filtration equipment. The skimmer chosen should be matched to the size of the tank. It is generally preferred that the skimmer be slightly over rather than undersized for the tank it will be used for. This will allow for heavier stocking, which we all usually do, and will also allow for a greater margin of error should something die in the tank. The skimmer should be run continuously and during the curing of the live rock it may have to be emptied daily until the large amount of organics released from the rock are removed. If there is one piece of equipment not to skimp on when setting up a tank it is the protein skimmer.

The last aspect of water quality that is of equal importance to the other two and which is often neglected is the use of high quality salt and a water purification device for the tap water used in the tank. There are many brands of salt on the market and the choice of which one to use should be based on the quality of the salt rather than the marketing behind it. Talk to successful hobbyists and find out which salt they use. Also buy a good quality hydrometer to make keeping the proper salinity easy. A means for purifying the water used in the tank and for making up new salt is also a good idea. While most tap water is fine for us to drink, we are not immersed in it and drinking from it constantly. As a result most marine creatures require water that contains less contaminants than we do. So to reduce these impurities the use of an additional means for purification should be used. For small tanks a small deionization unit is usually all that is required. For larger or more elaborate set ups, a reverse osmosis/deionization unit that may also contain additional means for purification, should be employed. These units are somewhat expensive but actually produce very pure water for only pennies a gallon, so over time they are actually much cheaper than buying purified water at a shop or grocery store. Starting with good quality water and salt goes a long way in enhancing the likelihood for success in the hobby.

Pictures related to this articles series can be found at here.

Mike Paletta is the author of The New Marine Aquarium and Ultimate Marine Aquariums. He has been in the hobby for over 15 years and has written numerous articles for Aquarium Fish Magazine, Tropical Fish Hobbyist and Aquarium Frontiers.