Techniques for Establishing a Nitrogen Cycle
A few nitrifying bacteria in a bottle products (not all) can help seed the system with nitrifiers. Most nitrifying bacteria in a bottle products do not contain the correct species of nitrifying bacteria for aquariums and do not work. Some nitrifying bacteria in a bottle products like “Dr. Tim's,” or “Tetra SafeStart” contain the correct species of nitrifying bacteria to seed a new system. These products contain bacteria that help maintain the nitrogen cycle at a pH above 6.0. They do not work for low pH systems (below 6.0). You cannot overdose on these products. Adding these products to the system shortens the time it takes to establish ammonia and nitrite oxidation to nitrate. Seeding with bacteria in a bottle can cut the time it takes to establish a mature nitrogen cycle in half.
If nitrifying bacteria in a bottle is used, remove all filtration media, and turn off the filters and aeration before adding the bacteria to the system. Allow one hour before turning on the filters or aeration so the bacteria can settle on the substrate. Do not install mechanical filtration in filters until the nitrogen cycle is well established (six weeks or more). This procedure will force the nitrifying bacteria to colonize areas outside the filter media.
Keeping the water temperature at 85° F (30° C) will speed up nitrifying bacteria reproduction.
Planting the new aquarium while cycling can help introduce beneficial bacteria to the system.
No matter which techniques the hobbyist uses, always maintain the pH on the basic (alkaline) side to maximize the reproduction of nitrifying bacteria.
Nitrate does not need to accumulate for the nitrogen cycle to be complete. In low-stocked planted systems, plants can utilize all the ammonium and nitrate produced by the bio-load and the nitrogen cycle.
During the time the nitrogen cycle is establishing, only water changes should be done. Do not clean filters or disturb the substrate. Waiting two or three months before cleaning the filter(s) allows all the beneficial bacteria to get established.
“Fish in cycle” is what most novice hobbyists do before they learn about the nitrogen cycle. The fish in cycle can be hard on fish and have long-term effects on the fish's health. Hobbyists can minimize the ammonia and nitrite by doing a significant percentage of water changes (90% or greater) when the levels become elevated.
When doing a fish in cycle, keep the fish population very light. Keep the stocking low with two guppies (Poecilia reticulata) sized fish per 10 gallons (40 L) for at least 35 days or when ammonia and nitrite have risen and fallen to 0 ppm.
Adding a quality nitrifying bacteria in a bottle product at the beginning of the aquarium setup can cut the time it takes in half to develop a mature population of nitrifiers.
The “fishless cycle” relies on introducing nitrifying bacteria in a bottle and feeding the system with ammonium chloride. Maintain a 2 ppm level of TAN until the nitrite spikes. Wait for the nitrite to drop to 0 ppm before adding animals.
Moving a filter, substrate, plants, and decor over from an established aquarium is the best method to establish a complete nitrogen cycle. Moving surface area from an established system brings over macro and microorganisms that can add instant biodiversity. A system setup with this technique often does not have ammonia/ammonium and nitrite spikes. This method aids in developing a diverse biome cycle; the other two techniques do not.