During the first month when an aquarium is set up, it goes through a phase called cycling. What is going on during this phase is extremely important to the health of the aquarium in the future. You will be culturing the biological filter by establishing the beneficial bacteria population which will serve to break down toxic ammonia and nitrite. Typically cycling takes between two and four weeks, however it can go as long as six weeks. During this period, it is very important not to do a water change or clean the tank. The dirtier the tank gets the better, since it means the bacteria will be more numerous and stronger!

Generally there is an indicator when everything is on a downward slope as the cycling period comes to a close, and that indicator is a large algae bloom. Don't worry! It’s a good sign. At this point the toxic ammonia and nitrite are being converted into nitrate which the main food source for algae. Now, when ammonia and nitrite test zero in a dissolved chemical test it means your tank is cycled. It is now important to perform a water change. After that, the tank is ready, and the prized fish and invertebrates can be slowly introduced into the aquarium.

The preferred method for cycling a new aquarium is by adding live rock. It is normally a fairly quick way to cycle a new setup since there is already a high population of good bacteria. However, if you are doing a fish only aquarium live rock would not be the best choice since you will need to take it out once the cycling period is done. With a fish only aquarium we recommend placing some fish food on the bottom of the aquarium and letting it rot. This decaying food will serve as a nutrient source for the bacteria and their population will grow. It generally takes a little bit longer than using live rock, since you are starting off with a smaller population of bacteria.