Dissolution rates of hydrated lime, Ca(OH) 2 in fresh, oligohaline, mesohaline and euhaline waters and its significance for liming of shrimp culture ponds

This study aimed at assessing the dissolution rates of hydrated lime, Ca(OH) 2 in fresh, oligohaline, mesohaline and euhaline waters and discussing its significance for liming of shrimp culture ponds. Appropriate volumes of seawater and distilled water were mixed to prepare oligohaline (1–4 g/L) and mesohaline waters (4–15 g/L). One gram of analytical grade calcium carbonate, CaCO 3 , or one gram of analytical grade calcium hydroxide, Ca(OH) 2 , were applied in 10‐L gallons filled with seawater (39.9 g/L), 10.7 g/L, 4.2 g/L and distilled water (0.0 g/L). The final TA of water was significantly higher for Ca(OH) 2 than for CaCO 3 only at salinities 4.2 and 10.7 g/L. It was concluded that hydrated lime, Ca(OH) 2 is a better liming option than agricultural limestone, CaCO 3 for moderately saline, hard and/or buffered waters (−4.5 ≤ Langelier saturation index, LSI ≤ −0.7). In poorly saline, hard and/or buffered waters (LSI < −4.5), limestone and lime would increase water TA similarly. Neither limestone nor lime should be applied on highly saline, hard and/or buffered waters (LSI > −0.7) because a TA decrease is expected.