Abstract: Fish effluents are main pollutant in aquaculture system,these waste products are also highenergy and highquality nutrients (N and P) and usable for seaweed.This paper studied the static purification of abalone effluents by Ulva P.K. The changes of water quality in Ulva tank were analysed.Results show that Ulva P.K. can uptake ammonia,nitrite,nitrate and phosphorus simultaneously.Ammonia removal is efficient,but the changes of COD is minimal.The decrease of ammonia in this system can be described by a model. Ulva P.K.can be used in intensive aquaculture system to clean water,save energy and provide an extra commercial crop.