I did the math on what I would need to fight evaporation on a 6-acre reservoir and it was looking like 16-20 gpm 24/7 from mid-May to late-September. It was 36 gpm before factoring in rainfall. I am working to put in a solar pump, but I don't think I will be able to get better than 8 gpm, so I am just going to plan to loose about 18 inches every summer.
