The term "bottom drain" is a misnomer. The concept was developed during the fifties and sixties in Japan. It was one of the first components of pond building and in those days, it was used in the literal sense. Each day the pond owner would methodically open the drain valve connected to the drain or tip or unplug a standpipe for rapid partial draining of the pond. The pond owner would typically release enough water to remove the waste that had collected in the drain over the previous 24 hours.
Although this is probably still the best application of the bottom drain, it is not, by American standards, the most time efficient way to rid the pond of these wastes. In fact, later designs and developments in pond construction in Japan linked bottom drains to settling chambers or some other form of pre-filtration as is now done here in the US and abroad. Ultimately, modern pond filtration systems use bottom drains for the same purpose as the original design, i.e. ridding the pond of initial waste build-up. However, the application is different in that the drain is in constant use. Therefore, the original nomenclature is lost.
Bottom drains have become more of a continually active component of the filter system. We at Aqua Art prefer to call this component an initial Water Intake System, or WIS. This is a more appropriate description of how bottom drains are now used.
The single biggest mistake people make in their rush to see the finished result is omitting the bottom drain. All the waste in your pond (if properly profile shaped) will collect near the drain or lowest location at the floor of the pond. Without a WIS, this waste collects and rots. Continual build-up of this rotting material will ultimately cause health problems for the fish and poor water quality. The most commonly reported reason for failure to install a bottom drain is an apprehension to put a hole in the liner. With every drain we sell, we provide full page instructions on how to correctly install a bottom drain, insuring leak- free service.
The tremendous amount of time you will save in maintenance is worth the effort.
See our web page for Water Intake Systems