i have a half acre pond almost full it is fed by run off and a wet weather spring which is slow 500 gallon a day max i have a 6 inch stand pipe and a 8 inch overflow pipe will this be enough? also wandering how close to the top of my dam can i hold the water level with the way my pond lays the diff. batween a foot from the top and 6 inches from the top makes a big diff. in the way pond will look when full.