pond filters

Why do i need pond filters 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"

Some will say "You do not need a pond filter, because the plants will keep the water crystal clear, after all nature has been doing this for years".

The problem with this statement is that nature doesn't build ponds with liners that are overstocked.

It is true some ponds that have fish are "balanced", but to be honest it very rarely works. I have seen some ponds where this works, but you can not see the fish because there are too many plants.

The easiest way is to have a filter and U.V.

To operate a filter you need to have a pump to circulate the water. We will assume you have one. (The pump should be left running 24/7) 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. (see fig 1)

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, and never even think of putting them in a washing machine (I have heard of this before)

I suggest you use a bucket of pond water, to clean the filters, not put the filters in the pond

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. Make sure you choose the right one.

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 an outer 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.

You may also want to see pond maintenance

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