Take soil samples in an M-shaped pattern over entire length and width of pond. The kinds of liming materials available in Maryland which are best suited for fish ponds include ground limestone, hydrated lime, and some by-product liming materials. The total oxide content varies from 37 to 56 percent. The total oxide content varies from 61 to 78 percent. It is normally quite finely divided and very reactive, and it does not have to be ground before use.
Liquid lime is a suspension of a very finely ground limestone in water.
Finely ground agricultural lime-stone is normally the best material for treating fish ponds. Since hydrated lime is so reactive and more concen-trated than most ground limestones, it may cause the water pH to go too high for a couple of weeks, which may result in a fish kill. If fish are not in the pond at the time of application, slaked or hydrated lime may be used so long as fish are not stocked until the pH returns to normal. Because the objective in liming is to first correct the acidity of mud at the bottom of the pond, the amount of lime you will need to apply can be determined in the same manner as the lime application rate for a field crop, lawn or garden. To begin with, you will need to know the soil pH, soil texture and location of the pond.