Whether you are building a new pond and need a new filtration system or
simply replacing your filter cartridge, PondPetsUSA has what you
We take great pride in understanding the unique needs that Koi require
when it comes to filtration. We can supply the latest products from
Answer, Cyprio, OASE, Nexus and more.
Filtration technology changes, and you can trust in us to be ready for
Follow the links at the top of this page to begin viewing our wide
selection of filters.
Clear water does not necessarily mean clean water, it may contain
colorless impurities, such as ammonia and nitrite, that are harmful and
can kill Koi. Koi excrete urine and produce feces, and ammonia is
excreted through the gill membranes. Also debris collects in
It is the job of the filtration system to remove waste which in the
wild would be diluted by the large volumes of water or washed away by
There are three types of filtration: Mechanical,
Biological and Chemical.
Most filter media have a mechanical function. Settlement chambers
allow gravity to drag the solid waste out of the water by slowing the
water flow. Such chambers usually come first in a filter. A vortex unit
provides greater settlement, the water moves in a circular movement
allowing solids to gather in the center where they can be removed. In
addition to baffle plates which slow the incoming water, brushes or
matting can be used to strain the water.
This relies on specific bacteria to break down toxic waste products
to less harmful substances. There are two stages in the breakdown of
ammonia, each stage involving different types of bacteria. The first
stage is the breakdown of ammonia to nitrite by nitrifying bacteria,
most important of which is Nitrosomonas. The second stage is the
conversion of nitrite to nitrate by Nitrobacter.
Activated carbon removes ammonia and other organic waste products by
adsorption, this means that the waste substances become linked to the
surface of the carbon. When the surface is 'full up' it has to be
Zeolite removes ammonia and nitrite from the water. A good feature of
Zeolite is that it can be cleaned by soaking in salt water (6g per
litter) for 24 hours and then reused.
If a large biological filter is present chemical filtration should not
be needed, but it is good to use while the biological filter is
maturing or isn't big enough for the pond.
Sand filter. Some Koi keepers use a sand filter as a final stage to
'polish' the water. The water is passed under high pressure through
sand and comes out very clear, bacterial activity also takes place in
the sand filter. Sand filters are expensive though, and you can't make
one yourself because of the high pressure involved.
Cleaning your pond filters.
Filters need to be cleaned occasionally to remove sediment, take
this into account when building one. Add a bottom drain to each filter
chamber so that sediment can be let out, it makes cleaning much easier.
Another thing that makes cleaning easier is to put filter medium in net
bags, not just pour it in all at once, as it can then be more easily
removed, one bag at a time.
One last important thing, never ever put tap water in a mature filter,
it will kill all the bacteria and you will have to let it mature all