As a general rule, about one ton of agricultural lime per acre is required to raise the pH one point. The lime should be distributed as evenly as possible over the entire pond. A common method for applying lime is to shovel it or wash it from a plywood platform while moving around the pond in a boat. Late fall or early winter is the best time to apply lime. A typical pond requires retreatment with lime every 3 to 4 years, although ponds with high rates of inflow and outflow require more frequent applications.
New ponds are easiest to lime while they are still empty.
Before the pond is filled collect soil samples for analysis following the procedure described above. Lime, if required, can be spread over the bottom of the pond and disked in before the land is flooded. If fish are not present or if agricultural lime is not readily available, hydrated lime can be applied carefully at the rate of 50 pounds per surface acre. Retreatment every few months is often required with hydrated lime. As with land and crops, the fertility of the water determines the productivity of a pond.