| Setting up and running a marine fish tank requires | | | | These are perhaps the most well known filters, and |
| several essential items, for example aquarium lighting, | | | | then keep the water clean by physically removing |
| live rock and a filter. | | | | particles of waste. There are two kinds: |
| For the beginner, there is what appears to be an | | | | External filters, as the name suggests, are positioned |
| almost bewildering variety of filters available, all of | | | | externally to the tank. They are generally easier to |
| different makes and prices. | | | | maintain and more effective than internal filters, and |
| Filtering methods can be split into three categories - | | | | have the advantage of not taking up any room in |
| chemical, biological and mechanical. | | | | the tank. Probably the most common variety is the |
| Chemical filters | | | | canister filter, which takes in water at the bottom, |
| These filters remove dissolved nutrients/pollutants | | | | passes it through a filter material and returns it via a |
| from the water, keeping it clear and free from | | | | pump at the top. |
| discolouration and odours. | | | | Internal filters are positioned within the tank, and so |
| Biological filters | | | | take up some available space; however they do tend |
| Biological filters are very important as they encourage | | | | to be cheaper than external models. Internal filters fall |
| the growth of bacteria beneficial to your tank | | | | into two categories. Airlift filters use bubbles to |
| ecosystem. Such bacteria convert harmful ammonia, | | | | create airflow, while undergravel filters cause air to |
| produced as a waste product of the fish, into | | | | percolate down through gravel using a system of |
| nitrogenous compounds known as nitrates. | | | | uplift tubes. |
| Mechanical filters | | | | |