Cary thanks for the advice i am quite a newbie at this. i am not sure the percentage of area that is 10' but if i had to venture a guess i would say its less than 20%. the pond is oval shaped with dimensions of 190' long and 70' wide. and since it was man made i would assume that the bottom is probably flat. if you think it best to leave at 6' that's what i will do, i was just concerned that i might be creating an oxygen deficiency at the bottom that would harm the fish.