The first step in building a pond is ensuring that waste products are efficiently removed from the system. The application of bottom drains is essential in this regard.
It is generally accepted that bottom drains are a must and should be fitted to all ponds under construction, those being modified, or alterations such as fitting a new liner. The number of bottom drains required will depend on the size and shape of the pond, and also the preferences of the owner.
Bottom drains are designed to be placed at the deepest part of the pond for the removal of the wastes and the settlements of the Koi.
Bottom drains count for the vast majority of the water circulation in a Koi when compared to that of a surface skimmer. Solids will sink out to the bottom of the pond in time, where ideally, they will be sucked into the bottom drain and fed to the filter systems where they will be extracted from the Koi pond system.
As a general rule, one bottom drain for the first 5,000 gallons and then one drain for every 3,000 to 5,000 gallons thereafter. Of course, the size of your pond will have a lot to do with this - as will the flow rate you want through your filter systems
Bottom drains - or the pipe work from the drain to the settlement chamber should not be too long. This is because although there is water flow through the pipe work, the heavier solids tend to settle out and can build up in the pipe work itself.