Pond filter

Why do i need a pond filter you may ask, well if you do not, fish waste will soon "contaminate" the water, also sunlight will accelerate the growth of algae turning your pond into "pea soup"

To operate a filter you need to have a pump to circulate the water. We will assume you have one. The easiest type of filter to run is the "box type" basically  your pump should be at one end of the pond sitting just off the bottom and the filter should be at the other, sitting just on the edge. The reason for this is so that you actually filter all the water in the pond not just a "pocket" between the filter and pump.

When you look inside a box filter you will see some coloured sponge layers and usually some type of "media". The sponge layers are of different grades the most course being at the top. This is for mechanical filtration.

Under the sponge layers the media will, after quite some time be colonised by bacteria, these bacteria break down the fish waste and make it harmless.

You should clean the sponge layers as and when required, use pond water not tap water to do this, since the chlorine content of tap water will kill the bacteria.

Where you Actually site the filter is up to you. Some people camouflage them or you can hide it out of site elsewhere. If you choose to bury your filter you may do so but do not put it below the pond water level. There are now some filters which are pressurised and ARE designed to be buried at or below the pond water level.

Ultra-Violet clarifiers (or u.v. sterilises they are also known) are basically an ultraviolet lamp (NEVER LOOK DIRECTLY AT ONE WHEN LIT) in a quartz sleeve encased in a tube. Water is passed through them from the pump in the pond then into the filter. They cause micro bacteria to clump together which then become too big to pass through the filter system hence they are removed. When a filter and u.v are used together you should get crystal clear water. 

Filters should be left running 24 / 7 since it takes some time to build up the bacteria and switching it off will mean you will kill them and the initial switch on will there for pollute the water with dead bacteria. This applies even during the winter, yes the bacteria will not multiply but they will not die either, if you do let them die over winter, you will dumping a load of dead bodies into the pool when you switch on in spring. You can switch off your UV though, and if you do this you should actually remove it to prevent ice build up from damaging the quartz sleeve. If you have a noisy filter* you may also want to read this (*Filter can appear to be more noisy in winter due to the lower background noise)

Not sure how big your filter should be then see here

The above is only intended as a guide and you should always refer to the manufacturers instructions for size of filter and flow rates. Koi need even more filtration, we suggest that that you consult a specialist if you intend on keeping koi (It's not that we do not know its just that it would take several pages to explain) for more information regarding koi we suggest  the British Koi Keepers Society (click the link)