A study was conducted to investigate the capacity in precipitating phosphorus of CaSO4, Ca (OH) 2 and Al2 (SO4) 3 to control growth of phytoplankton. At the same time, possible effects of these chemicals on shrimp were also evaluated. The results showed that all of these chemicals have high potential in precipitating phosphorus. Application of these chemicals in the shrimp tanks resulted in decreased phytoplankton densities as compared to the control. Mean densities of phytoplankton in CaSO4 , Ca(OH)2 and Al2(SO4 )3 treatments were ± , ± , ± , .
