Paddy Surface Flow used to Improve Fishpond Water

In improving fishpond water, constructed wetlands and multi-function ecological system generally are used, these methods improve fishpond water quality by surface flow and need a high cost in facilities' construction and operation so that affect them to be widely extended in the production practice. Aiming at the solution, an experimental study was made that paddy field was used for purifying fishpond water, the results showed that: 1) the improvement of aquaculture water by surface flow in the paddy field is related with growth period, effects in water quality improvement are best in the heading stage of rice, weakest in the yellow ripening stage; 2) the removal rate of some nutrients has a close relationship with their initial concentration in irrigated water from fishpond, the distance and velocity of the water flowing on paddy surface. The most significant efficiency on removal rate is flow path. So when the paddy field surface flow is used for water purification, the flow path should be considered firstly; 3) the paddy field surface flow has an oxygen-enriched function in certain amount of the aquaculture water, which is beneficial for aquaculture.