A seaweed biofilter/production system of being developed to reduce the environmental impact of marine fish farm effluent in coastal ecosystems as a part of an integrated aquaculture system. Several known seaweed taxa and their cultivars have been considered as candidate biofilter organisms based on their species-specific physiological properties such as nutrient uptake kinetics and their economic value. Porphyra is an excellent cadidate and shows efficient nutrient extraction properties. Rates of ammonium uptake were maintained at around 3 ${mu}moles{cdot}g{cdot}dw^{-1}{cdot}min^{-1}$ at 150 ${mu}M$ inorganic nitrogen at $10^{circ}C$. Ulva is another possible biofilter candidate with an uptake rate of 1.9 ${mu}moles{cdot}g{cdot}dw^{-1}{cdot}min^{-1}$ under same conditions. A simple uptake/growth and harvest model was applied to estimate the efficiency of the biofilter/production system. The model was deterministic and used a compartment model structure based on difference equations. The efficiency of Porpyra filter was estimated over 17% of ${NH_4}^+$ removal from the contimuous supply of 100 ${mu}mole{cdot}l^{-1};{NH_4}^+;at;100l{cdot}sec^{-1}$ flow rate.