When constructing a koi pond or even a garden pond that will be filtered the most important piece of equipment to be installed is a bottom drain.
Bottom drains are designed to remove the debris from the pond through pipework that is installed below the base of the pond to a filter system. This is the most effective way of removing dirt and debris from the pond and is fundamentally the most important piece of equipment that you will buy when constructing a pond.
The installation of a bottom drain is critical especially on koi ponds as the koi you will be keeping produce a significant amount of waste, by installing a bottom drain this waste can be removed under gravity to the filter system. The other option when building a pond is not to use a bottom drain and have the pump installed in the bottom of the pond (pump fed systems). The downside to this is that all the waste is liquidised as it passes through the pumps impellors and this makes it more difficult for the filtration system to catch these now very small particles resulting dimished water quality. This is not only unsightly for the pond keeper but detrimental to the overall water conditions in which you are going to keep your prized fish.
We all know that building ponds is not a cheap and a significant amount of investment is required not only for the pond but for all the additional landscaping that may be incurred as part of the build process. When looking at budgets a bottom drain is something that should be compromised on, as the cost to add one later is significantly more expensive than installing one in the first place. In some circumstances it can even result in the complete rebuild of a pond. Other equipment such as filters, pumps, UVs etc although important can all be upgraded at a later date without having to destroy your garden or pond.
With the installation of a bottom drain/drains, as mentioned above all the pipework is installed below the base of the pond. If you install a Spindrifter, which has an air dome for oxygenating the water, there will be no unsightly pumps, pipes, airline or airstones in the pond, just your fish!
There are several bottom drains on the market at the moment ranging from approximately £20.00, the best of which is the Spindrifter. Although more expensive, due to the rising air from the air dome, the Spindrifter works potentially 30% better than a standard bottom drain.