Pond Filtration

Organic matter is continually added to a pond by fish waste and dead leaves, left alone it can become toxic and turn the water green.

A pond filter acts as a waste water treatment system, good bacteria colonise the filter and breakdown toxic organic matter (ammonia and nitrites) into nitrates which is plant food.

To be effective there must be sufficient bacteria present in the filter to match the size of the pond and the number of fish. A pond can not be over filtered, so always choose a filter that is the correct size or larger for your pond and select a pump that will turn your pond water over every two hours.

The filter bacteria rely on the flow of water to live, hence the pump and filter must be run 24 hours a day, 365 days a year.

Filters will need to be cleaned periodically, always use pond water as tap water may kill the bacteria.

It takes time, (approximately 6 weeks), for bacteria to fully colonise a filter, this can be speeded up by adding a filter boost, initially and after each cleaning.

An efficient filter will help to keep your fish healthy and active in a clean environment.

A pond filter on its own will not necessarily keep the water clear as suspended algae will feed on the nitrates, turning the water as green as pea soup, for this reason most filters incorporate a UV clarifier. This destroys the algae as it passes through the filter leaving the water clear. A separate UV clarifier can be added to an existing filtration system.

Together, the pump, filter and UV clarifier will keep a pond both clean and clear making it a joy to watch healthy active fish.

There are three basic types of filters

Gravity Return

These are efficient filters that sit outside of the pond often at the top of a waterfall. The pump is in the pond and pumps water to the filter, which cleanses it and it flows back to the pond by gravity, either down a pipe or waterfall. Hence the filter must be positioned higher than the pond.

Pressurised Filters

These are the most recent innovation in filter technology. They can be positioned anywhere outside of the pond, being pressurised, they do not have to be higher than the pond so are easier to disguise. Some models have an easy clean feature, these can be cleaned periodically without stripping them down, making for very simple and clean maintenance.

Gravity Fed Filters

These are a more specialised filter, often incorporated into koi ponds. Water flows from the pond to the filter through a large bore pipe usually connected to the pond by a bottom drain. The filter is at exactly the same level as the pond as the top water level is the same in both. A pump rests inside the filter retuning the water to the pond so creating a continual current through the pond and filter