Article 2 - KOI Pond Filters -
Koi Pond Filters
All water contains impurities, such as ammonia and nitrite, that are
harmful and can kill your Koi. Like any other living creature, Koi excrete
urine and produce feces, and ammonia is excreted through the gill membranes.
In the wild, natural ponds handle these impurities by diluting them
in their large volumes of water, or washing them away in the running
water that often feeds ponds. In your backyard, however, you'll need
to have a filter to replace what Mother Nature does herself.
Mechanical filters use a filling, called media, and settlement chambers
to clean and purify the water. Settlement chambers allow gravity to
drag the solid waste out of the water by slowing the water flow. These
chambers usually come first in a filter, pre-treating the water before
sending it through the media to remove the finer particles.
This filtration method uses specific bacteria to break down toxic waste
products and convert them to inert particles. This process uses a two-stage
approach. The first stage breaks down ammonia to nitrite using nitrifying
bacteria such as Nitrosomonas. The second stage is the conversion of
nitrite to nitrate by Nitrobacter.
Both of these bacteria need oxygen to live. Since sediment building
up in the filter depletes the available oxygen levels, it is important
to keep sediment to a minimum by having a settlement chamber first and
by cleaning the filter out occasionally.
A variety of filter media are available including gravel, matting,
hair rollers, foam, and canterbury spar. They all provide s good surface
for the bacteria to live on. On the down side, a biological filter will
take weeks or even months to mature. You can buy cultures of nitrifying
bacteria to l speed up the process.
Am ammonia and other organic waste products are removed by activated
carbon using a process known as adsorption which causes the waste particles
to become linked to the surface of the carbon. When the carbon surfaces
can hold no more they must be replaced.
Zeolite can also be used to remove ammonia and nitrite from the water.
Zeolite is "rechargeable" as it can be cleaned by soaking
in salt water for 24 hours.
If a large biological filter is present then chemical filtration is
not normally required, but is a good alternative to use use while the
biological colony is maturing.
Some Koi owners use a sand filter as a final stage to 'polish' the
water. Water passes through the filter, under high pressure, and comes
out very clear. Desirable bacterial activity also takes place in the
sand filter. However, sand filters are expensive to operate and clog
too easily to be practical for fish or koi ponds.
Bead filters are an excellent alternative to sand filters. They
are similar in function, but very different in terms of the interior
plumbing and media. Instead of sand, bead filters are filled with
thousands of small plastic round beads. The function of these
beads are twofold. One function is to help trap particulate matter
in the water, and prevent it from passing through the filter, while
still allowing the water to pass through. The second function is
to provide a large surface area for the beneficial bacteria to grow on,
this bacteria removes ammonia and nitrite (fish waste) from the water.
Filters need to be cleaned occasionally to remove sediment. Most good
filters have a bottom drain for each filter chamber so that sediment
can be let out. Here's a timesaving tip: Put filter medium into net
bags so it can then be easily removed from the filter later..
One last thing, NEVER put chlorinated tap water in a mature filter, it will kill
all the bacteria and you'll be back to having to grow a new colony all
An ultraviolet (UV) system kills bacteria, parasites and algae living
in your pond. In order for most harmful bacteria to reproduce, it must
be able to float freely, in your pond, in order to find a suitable host.
An epidemic of bad bacteria can spread throughout a pond and cause infection
in your Koi.
UV systems are easy to install. The units are usually installed in
the plumbing system somewhere after the pump and before the water enters
the pond. Although your UV system should run along with your pump, 24
hours a day, it may not be necessary to run the lamps year round. UV
systems are environmentally safe and not harmful to humans.
For more information about Koi Pond filters, please visit us at www.macarthurwatergardens.com
Until then - Happy Pondkeeping!
Brett Fogle, Owner
MacArthur Water Gardens
Back to Article Directory