Sometimes your biological or mechanical filter does not effectively clean wastes from your pond. This is when you have to resort to using what are called chemical filters. These are also sometimes called biological converters. These are solutions or powders that are added to your pond to correct common problems such as an excess of nitrates, an excess of ammonia,
Every koi pond owner should invest in a ten dollar nitrate test. This test should be done at least once a month but ideally once a week. A simple test at the right time may prevent a small problem from becoming a catastrophe.
You can buy all kinds of tests to monitor the water quality in your pond including:
- PH balance
- Ammonia
- Nitrate
- Alkalinity
- Salinity
- Chlorine
Do not confuse the terms water quality and water clarity. Crystal clear water can contain compounds that are deadly to your fish. Green water, caused by excessive phyto plankton growth can actually be beneficial to the fish although not very beneficial to the pond keeper who can’t see them. Water clarity can give some indications as to mechanical filtration effectiveness but it does not necessarily tell you what is happening with the chemical make up of the water.
A pond with a biologic converter and filled with Koi is a rather complex, and delicate eco-system. Each component of this system requires the other components to perform its job. Fish waste and bacteria and fungi to ammonia compounds convert other organic waste. These compounds can be toxic to the fish, which then can die a very visible, hard-to-watch death.
However, if your koi pond has a healthy biologic converter it should be populated with mitrosomonas bacteria. This is the type of bacteria that greedily consumes ammonia and converts them to nitrites. Unfortunately, the nitrates are just as toxic to the fish as the ammonia. Again, the biologic converter comes into play with a population of mitrobacter bacteria that convert the nitrites to nitrates. The nitrates are basically inert to the fish but usable by plants and algae within the pond. As the plants and algae grow and the Koi eat them, the cycle of self-cleaning starts all over again.
Nitrosomonas and nitrobacter bacteria are aerobic bacteria that require oxygen to convert their “food” to energy just like the fish. This is why an ammonia or nitrite filled pond can smother both and leave you with a lifeless swamp.