Hi all, I was going to use my old CC then add two bags of live sand. After some reading I am concerned. The CC I have has some large pieces in it along with the fine. So after time the CC will rise and could trap uneaten food. So I think I would rather have a sand bottom. The tank is 55 gal. How much base sand and how much live sand. I heard you want about 3-4 inches ??