Letting us know where you are at will help. in Boston evaporation is playing little effect right now, if you are in a 100+ degree desert, then evaporation plays a large role. Also what is the surface area? Is the water deep with a small surface area, or is the water shallow with a large surface area?
Why do people not respect us as they do other tradesmen? Because every Tom, Dick, and Harry doesn't think he can be a plumber or electrician!