Well thanks, if i were doing another one, here is what i would do different. 1st. I would eithier build an external overflow, by cutting the top 1/2 off of the back glass and build an overflow on the back of the tank to take it to the sump. That will open a ton of usable space in the tank. 2nd. I wouldn't place my returns in the bottom of the tank. I would drill in 4 returns across the back and cover the pipes in cement work, enclosing them into the rocks. 3rd. after pouring in the floor, i would try and build the rockwork, and caves using layers of the foam used on the walls and glue, then cover the entire thing in 1/4 inch of the cement, a layer at a time, not using the accetorator. It worked good but was expensive for what it did. The foam will be fine staying inside the rock. It will act the same as a very pourus liverock wall. The foam is individual bubbles, so large debris can't go past the surface, only the microscopic stuff can go through it, plus the entire surface is covered in cement. Ant caves would need to be pre coated on the underside before cementing them into the structure. I also wish i had used bigger bulkheads for my overflow. The 3/4 inch ones just don't flow much. I have got the outside part of an external overflow hanging on the back, with the U- tube going into my internal overflow to make up for it.
I don't think i will ever put up another tank, no matter what size it is, without doing the cement treatment to it.