It functions as a trash guard that prevents large debris from flowing into and plugging a pond's overflow pipe. It deters beavers from plugging the overflow pipe. Such a barrier prevents grass carp larger than eight inches and adult game fish from leaving a pond through the overflow pipe.
In many situations, the use of grass carp is an economical, long lasting, and effective option. However, grass carp are not appropriate for every pond. Whether grass carp should be stocked in a pond or not, depends on the goals for the pond.
Diagram of a polyethylene pipe floating livestock water access point. View Publication