| Among the different koi filter models, there are | | | | could increase and this would favor the growth of |
| biological filters. These are specially made to sieve | | | | algae that may inhibit the growth of the koi and |
| off organic and particulate matter. The bio-filter | | | | eventually choke them off. |
| uses media that is laden with anaerobic bacteria | | | | The most popular koi filters are the down-flow, |
| to break down dangerous toxic matter into | | | | up-flow, recycling, pressurized and submersible |
| by-products that are harmless. If your koi pond is | | | | types. Most keepers experience problems with |
| a big one and doesn't have a bio-filter, its | | | | their filter operations when it comes to channeling. |
| environment will be harmful to the koi fish due to | | | | The filters use different media to trap other |
| the build-up of decaying leaves, fish waste, pond | | | | matter and allow water to pass through. When |
| creatures, and other matter that settles at the | | | | these matters clog the filter, water will find its |
| bottom. | | | | way using another path until it can no longer pass |
| The size of the koi filters used in the pond should | | | | due to clogging. As a result, the water will look for |
| be directly proportional to the number of fish in | | | | a path where there is least resistance and will |
| every gallon. More fish means more waste and | | | | make it the natural way of passing over the pond. |
| therefore you will need a much larger filter. | | | | After this, even if you unclog the filter or replace |
| However, it is not necessary to have a filter if | | | | it, the water will have already found a permanent |
| you have a small pond. This can be confirmed by | | | | channel that avoids the filtration process. |
| investigating the natural habitat of the koi. Such | | | | A down-filter operates on the law of gravity as |
| habitats have no filters and yet many fish survive | | | | opposed to up-flow or pressure. When matter |
| in the environment. | | | | clogs the filter media, gravity cannot force the |
| In case your koi fish population becomes very | | | | water to pass through the clogged channel at the |
| large such that your pond starts spilling over, put | | | | same rate that it is being pumped through it. As a |
| off food supplies, the koi would naturally thin out | | | | result, the water will find its way back into the koi |
| until a small population that can be sustained by | | | | pond unfiltered by spilling out of the overflow |
| the prevailing environment is reached. With such | | | | drain back. |
| an occurrence, there would be an imbalance in the | | | | The most efficient koi filters are the pressurized |
| nitrogen cycle, as much nitrate would be produced | | | | filters, as they do not require any maintenance. |
| from the fish waste. As a result, the water pH | | | | |