Koivet.com | Fish Health | Dr. Erik Johnson

The Cycle is the natural process in which the fish excrete wastes (fish poop and pee) into the pond water and Mother Nature has to deal with these wastes before these compounds pollute the water and make the fish sick. The process is conducted by two major classes of bacteria. Nitrosomonas takes the Ammonia and breaks it down into Nitrite. Nitrite is broken down into Nitrate by Nitrobacteria. It’s not very complicated when you think about it. A three step process with two bacteria who do the whole job. Now, these bacteria live in a film on the sides of your pond, on plant surfaces, and especially in the filter on the media inside. If you have a filter with a sponge in it, the beneficial bacteria which complete the cycle will live on the sponge. If you have a bead filter, these bacteria live as happily on the beads.
With filters, the whole focus is centered around getting beneficial bacteria to grow and live in your filter media. If your filter gets clogged with solid wastes, the bacteria are “choked out” and the filter becomes ineffective. Filters should be cleaned outside the main pond in a bucket with pond water to avoid killing the beneficial bacteria with the chlorine which occurs in municipal water supplies.
SHORT AND SWEET: When you initially set up a new fish pond, there will be Ammonia and Nitrite accumulations which will threaten your fish unless you’re prepared.