Pond Filters

Pond filters. What pond filters do, how to install a pond filter.

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 is the media the bacteria will live on. These bacteria break down the fish waste and make it harmless. (imagine never flushing a giant toilet)

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 as the pond will empty.

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. Some even have an out let to waste, which usually means moving a lever, and pulling a handle which then cleans the filters and the dirty water goes to waste (it is also good for any flowers)

Ultra-Violet clarifiers (or u.v. sterilisers as they are also known) information is on this page

Filters should be left running 24 / 7 since it takes some time to build up the bacteria (it can be UP to 6 weeks) Switching it off will mean you will kill them. because you have taken away their food and oxygen supply. If you do this, next time you switch on the filter pump you will  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.

The reason it is done like this is to prevent any "dead areas" where water may stagnate