The main components of green seaweed polysaccharides are starch and cellulose which considered as potential raw material for bioethanol production. The effects of cultivation time, stocking density were studied from January to December in 2009-2010 at 250, 500, 750 g wet/m2 in the pond. Growth rate decrease with low or high in the stocking density. The highest growth rate were obtained at 500 g wet/m2 for all species and range 4.76.8 percent/day. The best cultivation time for each species was determined, Ulva torta was from January to April, Chaetonwlpha linum was from May to October and Cladophora socialis was from August to December. The results indicate that to have a scientific basis for the proposed method of seaweed cutivation with high production of 15.48 ton dry/ha/year in biofiltering systems of shrimp cultures.