Greg :

On all our ponds alka. in normal state is 9-10ppm. It is only through an ag lime program that we can get to 20ppm. We try to get it higher but with a reasonable program can only get to 35-40 max. Over 18-24 mths it will fall to the 20 level. We add more ag lime when it gets to about 25 and it will kick in in time to keep it above 20. We do not have high flow through but a little so that is not a big factor.

I have posted my thoughts. I would add lime even if we did not fertilize for the stated reasons. We do not use hydrated lime and will not unless an emergency occurs. IMO it carries to much risk in ponds and it does not last. Instead you get an alak. spike which dissipates quickly. In addition other bad things can happen quickly if you make a mistake in application --like killing your fish. On occasion I will use pelletized lime which is like concentrated ag lime (2.5 to 3 x ag lime)which comes in bags. ewest