Tony, I edited my original post regarding evaporation because I realized my flaw. I have looked at a lot of rainfall/evap patterns and knew 3/4 seemed high and it seems that I didn't take the dirt weighing down my bucket into consideration. My tank is dropping 3/4" a day also and I have one side that is in caliche soil. 3/8" isn't good for seepage but it won't look nearly as bad in the winter months when evap is often less than .10"/day. Have you done any cation exchange tests on your soil?