Question about styrofoam/eggcrate to raise rock
I have a rock structure I would like to lift up a few inches before I put my substrate in. I have heard of people using styrofoam, and plastic light diffuser.
I have two questions. I'm really not looking to glue 2-3" of styro foam to the bottom of my tank. I'm afraid if I tried to use it without gluing it it would float. Anyone done this?
Option two is to use the light diffuser. It seems sort of rough, does it stratch the bottom of the tank? And is it ok to use 4-5 layers of it b/c I think it's only a half inch thick, to get the height i'd like? I'm afraid of it being unstable.