The present study aimed to evaluate the effectiveness of the shell powder of Anomalocardia flexuosa and Crassostrea spp. as correctors of the alkalinity and pH of aquaculture water. At the end of the experiment, the alkalinity and pH values of the oyster powder treatments (82.00 ± 18.00 mg.L -1 of CaCO3 and 8.31 ± 0.08, respectively), Venus clam powder (89.33 ± 13.20 mg.L -1 CaCO3 and 8.35 ± 0.03, respectively), and sodium bicarbonate (166.00 ± 2.00 mg.L -1 CaCO3 and 8.67 ± 0.02, respectively) differed (p<0.05) from those of the control (36 ± 0.00 mg.L -1 CaCO3 and 7.73 ± 0.01, respectively). The oyster and Venus clam powders reacted similarly (p>0.05), increasing the alkalinity and pH values; however, both had higher values than those of sodium bicarbonate (p<0.05). The reaction time of all products was 24 h after their addition, showing a significant increase in alkalinity in the first 24 h, with stabilization at the end of 15 days. In this sense, there is great potential for the use of oyster and Venus clam powders for the correction of alkalinity and the maintenance of pH in aquaculture.