BTB,
Generally your county agent can arrange for the tests and if you tell them the intended use, they can make a specific recommendation on tons/acre. On my ranch, it takes 4 tons per acre to get the water cleared up.
I've built three ponds now myself and in each case, without exception, about three weeks following the proper application of ag. lime, the pond water is beautiful rather than muddy brown. It does clear the water and promotes efficient utilization of nutrients in the food chain.
