The filter is probably the most important part of your aquarium. No matter what type of filtration (mechanical, chemical, biological) you use, without good a biological filtration base, your tank will quickly turn into a disaster.
The biological filter is a living, breathing organism. It consumes oxygen and waste materials in your tank and excretes waste of its own. The more oxygen and water that pass over the bacteria, the better the filter functions. The biological filter consists of a collection of naturally occurring bacteria that work in unison to transform ammonia into nitrite and then into nitrate. Ammonia and nitrite are highly toxic to fish. The ammonia in an aquarium (and in the oceans) is generated from the metabolic wastes of fish, invertebrates and bacteria. The biological filter in your tank has to go through three Biological Cycles in order to generate and house a sufficient number of the right bacteria in order to convert the ammonia and nitrites into nitrates before they are even measurable. The "old process" of developing the bacterial filter consisted of setting up the tank, do whatever you had to do to keep the ammonia levels high (there are reports of people drinking a beer and then urinating into their new aquariums every so often, rather than sacrifice a number of fish) and wait for the two month process to run its course. When the ammonia and nitrite levels tested at zero and the nitrates were measurable, you started adding fish and inverts. The key thing to remember is that your biological filter process will not begin without ammonia being present. Fish and other living creatures provide the ammonia to trigger the process, remove the fish and the process stops. As a matter of fact, if you have a "conditioned" system and you remove all fish and living creatures, leave it empty for a prolonged period of time, your biological filter dies and you have to begin all over again.
Thankfully, we have progressed far beyond those days. Today, there are a number of "cultured bacteria" products available at your local pet store that can be added to the tank at the time of fish introduction to a new system. These are the same bacteria that drive the oceans' biological filters, and one of the best on the market is Hiatt Distributors Limited "Right Now". This, when combined with Hiatt's "Tri-Pelletized Activated Charcoal" will give you an immediate start on your biological filter. While you are creating your filtration system, add a "flowing tube", driven by your air pump. Fill the tube with charcoal and insure that, once your tank is set up and running, the air and water are flowing freely through the tube. Let the filter run for a day or two, until the water clears up. Drop in a few fish and follow the instructions on the "Right Now" container. Perform daily tests for ammonia, nitrites and nitrates and record them in your "Aquarium Logbook". The test kit we recommend (we've tried a lot of them over the years) is AquaTru by Kordon. They offer a Saltwater Master II Kit that is perfect for your needs. Your tank should "settle" in 3 or 4 days. When the ammonia, nitrites and nitrates test at zero you can start adding more tank critters, a few at a time. The combination of the "Right Now" and the "Tri-Pelletized Activated Charcoal" should keep your nitrate level at near zero.
We recommend a fairly coarse sand (or fine gravel) medium for your U.G. filter. We have used a material consisting of dead, chelated coral (looks like Quakers Oats) which we have brought up from depths of 40 feet, and have found it to be an excellent medium for our 55 gallon glass tanks. It doesn't pack down, lets water flow freely through it, provides a good surface area and cleans easily. The calcium in the coral also helps stabilize the pH in the tanks. Your local pet store should have a satisfactory material available on their shelves. Follow the directions that came with your new filter and pump.
