By the way, pay no attention to what I say. Better you have experts help you. But that does not stop me from having an opinion.
My main pond my NRCS agent recomended I line the bottom of the pond with stock piled top soil if I wanted non-turbid clay looking water (as thin of layer I could get spread). It worked as that pond has not had clay turbidity problems like other ponds that were simply left clay bottom. Topsoil particles (silt and sand) are many times larger than clay and will precipitate out of the water column better. But topsoil does have nutrients in it so if it is very fertile topsoil could add to nutrient problems.
My forage pond I essentially completely lined with crushed limestone that consists of rocks up to 1 inch all the way to ag lime fines with probably 10% ag lime. That pond is great. That is why I say it is almost impossible to get to much ag lime. Your pocket book will run out before you get too much applied. It has limestone 3" deep (called AB3 at the local quarry). If you put lime a foot deep you would just have a pond that acted like a water filled limestone quarry, ag lime simply being ground up limestone rock.
My old refurbished pond had clay bottom and was turbid. A couple of applications of ag lime from the bank and a years time cleared it.
Now hopefully someone will come along with some proper answers. That is just what I did. Others results could vary.
