Scott's 270g aka Project Mayhem

[lockrookie]

I too think your good with the 1/2" foam the idea is for the foam to give and keep it level and it will do the trick. Especially with the plywood under the tank it should have less flex and stress points for the glass in general. I'd say good to go. You could always do a fresh water test before you fill with ro if you want to be sure.