When researching tank manufacturers I noted that one recommended placing the tank on 2 layers of plywood with the top piece free floating so that you can shim the top sheet. I'm having a hard time seeing how this is better than using 1 sheet and shimming between it and the 2*4 frame. You could shim it before screwing it down or just free float it, if the frame is strong it doesn't need the plywood to act as cross bracing and 1000+ of water is going to keep it from shifting. This approach will be significantly easier for tanks eith walls on 2 sides which likit access. Does anyone have experience or thoughts regarding this method?
