Josh your application rate seemed spot on and I imagine you went more heavy at the base of the dam since you knew you had seepage there. I also bought 3 units but my pond was perhaps 1/4 acre instead of your 1/2 acre. I probably could have gotten by with 1.5 units or even 2. I ended up putting in 2 units but had to go and retreat pretty much the whole pond to use up the entire 2nd unit. I intend to retreat the remaining 1 unit for 'good measure' when I get a nice calm day.
