A Low‐Flow Self‐Cleaning Drainage System for Fish Rearing Tanks

A float–stopper mechanism was designed to drain fish holding tanks directly from the bottom. Unlike traditional, top‐drawn standpipe systems, it allows continuous flushing of settled solid waste. It also prevents the accumulation of these wastes between the two standpipes that are used in bottom‐drawn, double‐walled standpipe systems. When suspended solids are forced upward between the outer and inner standpipes of such systems, a minimum velocity must be maintained to prevent sediment accumulation. This minimum velocity determines the minimum flow rate through the tank. The system described in this report flushes well over a wide range of flow rates.