It is very simple to keep Nishikigoi if you have equipment for
filtering and cleaning water. It is advisable to consult a Koi dealer or specialist as to which type of filter is most
suitable for you.
Filtering the ponds various forms of debris and waste products takes several steps and can be
done so many different ways. The better we incorporate the basic features, the more likely we are to have
success.
When filtering waste from a pond, it is better to Mechanically filter it before continuing onto the
Bio-Filtration. This permits the Bio-filter stage to perform optimally.
Mechanical filtration of a Koi
pond.
Most Koi pond 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 (shown to the left) 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.
Examples of mechanical
filters:
- Skimmer (Olympic Wide-Mouthed Skimmer shown to the right)
- Filter Media
- Filter Brushes
- Pump Baskets
- Vortex
Chambers
Surface debris is removed using skimmers. Since debris settles, using a bottom
drain as a source for intake permits the debris to be removed from the pond to some type of separation chamber. Screens
or baskets in front of pumps are important in keeping pumps from clogging. They also prevent damage to the pumps
impellors.
Biological filtration of a Koi pond.
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.
Both of these groups of bacteria are aerobic (needing oxygen to live), sediment
building up in the filter will deplete the oxygen levels so it is important to keep sediment to a minimum by having a
settlement chamber first and by cleaning the filter out occasionally (but not using tap water as the chlorine will kill
the bacteria).
A variety of different media are available to put in the filter, materials such as gravel,
matting, hair rollers, foam, and canterbury spar are all suitable as they provide lots of surfaces for the bacteria to
live on.
A biological filter will take weeks or months to mature, cultures of nitrifying bacteria are widely
available and will speed up the process.
Bacteria: There are both Pathogenic (Bad Bacteria) and Non pathogenic
(Good Bacteria) Aerobic (require oxygen) and Anaerobic (absence of oxygen) bacteria. Since pathogenic (generally
anaerobic) bacteria cause disease, it is preferable to introduce and promote growth of a larger number of non pathogenic
aerobic bacteria.
The bio-filters need to provide adequate media surfaces for bacteria to flourish when
environmental demands increase. Over stocking a pond is a common mistake made by pond keepers that ends with fish
mortality. Most lakes have a smaller ratio of fish to water volume then the ponds most of us create in our own yards.
Since the good bacteria attach to and grow on the media, flowing water helps wash away decaying bacteria and bring fresh
chemicals. The more media surface, the more good bacteria the filter can support. Bacteria is abundant throughout the
pond in the water and on all pond surfaces. Increasing the oxygen levels also benefits the ability for bacteria to
flourish.
Chemical filtration of a Koi pond.
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 replaced.
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 Koi pond
filter. 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 over again. |