| If you are building a koi pond, you will need a | | | | Nitrogen is a gas that makes up about 80% of |
| suitable pump and filter to help keep the water in | | | | the air that we breathe, and when it forms |
| the pond clean, clear and healthy. The basic | | | | compounds with other chemicals, it plays an |
| choice, as you will find out from outlets that have | | | | extremely important role in the environment. |
| a good range of fish pond supplies, is between a | | | | Proteins, which are part of many different living |
| mechanical filter and a biological filter. While both | | | | tissue types, are an example of compounds that |
| operate with some type of suitable pond pump, | | | | contain nitrogen. Nitrites (NOâ,,), which plants |
| the way these filters work is completely different. | | | | convert into protein, form toxic compounds that |
| Mechanical filters are similar to the type of filter | | | | irritate and are harmful to fish. But when the |
| that we use in swimming pools, in that they are | | | | bacteria in the filter feed on it, it is converted into |
| designed to sieve out dirt, solid waste and algae. | | | | a nitrate (NOâ,?) that is relatively |
| It is a much simpler unit, and therefore less | | | | harmfulness and is absorbed by certain pond |
| expensive to buy, install and run, than most | | | | plants as food. Ammonia is another toxic waste |
| biological filters. Powered by a pump, water is | | | | product, and it is excreted by fish and also |
| drawn into the filter where it passes through | | | | formed when plant matter, like leaves and grass |
| some type of filter media, for example foam, | | | | cuttings, decay in the water. Like nitrites, |
| coarse sand or gravel. It is then pumped back into | | | | ammonia is toxic to fish, but is food for bacteria. |
| the pond. Suspended grit, waste products from | | | | In addition to the bacteria in biological filters, |
| fish and algae collect in the filter medium, which is | | | | various single-cell organisms and even some larger |
| cleaned and changed regularly so that the filter | | | | creatures, like water fleas and worms, feed on |
| continues to be effective. | | | | different types of waste that get drawn into the |
| Mechanical filters are often used in ponds where | | | | filter media. Some of these also feed on algae, |
| the pump is also used to generate a fountain or | | | | which any pond owner knows is the biggest |
| waterfall. So when the pump is switched off, the | | | | culprit when it comes to green, murky water. |
| filter stops working - no problem. But if you opt | | | | Over time, floc, a brownish fluffy sediment, builds |
| for biological filtration, the filter must run | | | | up in the filter. For this reason biological filters, like |
| constantly. | | | | mechanical filters, must be cleaned regularly. |
| How biological pond filters work is that the water | | | | There are various different types of biological |
| passes continuously through a bed of filter media, | | | | pond filters, some of which are housed in the |
| where the unwanted waste particles settle - just | | | | water. The simplest though is an above-ground |
| as in a mechanical filter. But the filter media is | | | | unit that has a single-chamber tank filled with |
| designed to allow natural organisms to thrive. | | | | layers of different filter media. The water is |
| Bacteria and single-cell organisms found naturally in | | | | pumped into the tank from the pond - it flows |
| the pond water, flourish in the filter, and help to | | | | through the media and then back into the pond, |
| break down the waste. It is the most | | | | either through a pipe, or via a waterfall. You will |
| environmentally friendly process you can imagine. | | | | find filter media alongside all your other regular fish |
| The organisms in biological pond filters play a vital | | | | pond supplies. |
| role in what we know as the nitrogen cycle. | | | | |