If you want to keep your pond clean and healthy, then a pond filter is the answer. There are a lot of different types from which to choose and choosing the right one all depends on what you expect out of your filter. Firstly, a word of warning. Pond fountains often state that they have a built in filter. This usually comprises a small piece of sponge. Its purpose is to stop small bits of debris entering the fountain head and blocking it up. That is all it does. It will not keep your pond clean and will not eliminate green water. This requires a different type of filter. Let’s look at what is available and what would be the best buy for your pond and your budget.
A pond filter usually comprises either a submerged all in one pump and filter, an external pressure filter or a ‘black box’ external filter.
For smaller garden ponds, a submerged in pond pump and filter will suffice. These all in one pump, filter and Ultra Violet combination units are ideal for the smaller garden pond or water features as they are so easy to install and maintain and easily hidden. The Hozelock EasyClear and Oase Filtral are good examples of this type of filter which contain a pump, UVC and filter in one unit.
For many larger garden ponds, the traditional ‘black box’ filter is ideal. The black box is just that, a box containing filter medium, an inlet hose into which water is drawn by a pond pump and an outlet hose through which water is passed back into the pond. They will also often contain a UVC to help clear green water.
They are usually sited slightly away from the pond so that they can be hidden behind plants or a low wall. They can often be partially buried into the ground. To do this, look for models with a top inlet and outlet. Water is pumped in at one end from a pump situated on the floor of the pond. It then passes through a UVC (ultra violet clarifier) which causes green algae to clump together into larger lumps. From there it passes via a spray bar over the first filter medium, often coarse sponge, which traps these green clumps of algae and any other water-borne sediment. Often 3 different grades of sponge are used to trap different sized particles.
The water will then pass through another chamber containing large pieces of filter medium or bio media such as flocor, in which friendly bacteria will consume harmful bacteria and pollutants, further clarifying the water. It then passes out through the outlet hose and back to the pond. In some more advanced versions, water will pass through brushes before the foam to remove larger particles.
Pressurised filters are a lot smaller and so are extremely popular for small to medium sized ponds. As they can be partially buried, they are a lot easier to hide than traditional box filters. Not only can they be situated almost anywhere around your pond, they can also be easily covered up with plants or a cover making them easily disguised. Pressurised pond filters usually have a built in UVC (ultra violet clarifier) which helps to eliminate green water. Pressure filters are also easy to maintain, many having a built in self-cleaning device. The Oase Filtoclear is a good example.
Koi ponds will usually require something a little more elaborate than this. These will be dealt with in a separate article.
For more advice and some great deals on pond filters, you may like to see some of the following web sites which we recommend for quality as well as price.