Egg Crate Under Rockwork ?

[DiverDude]

Some interesting points have been made.

I was only planning on putting small(ish) sections of Egg Crate (EC) under the rock and not over the entire bottom. I'd like snails, my sea star, bulldozer shimp/Goby to be able to dig away without the impediment EC might cause.

The though was that where there was rock, the EC would displace stress and PREVENT any/all of the aforementioned critters from undermining it and causing issues.

The acrylic is a really good idea too as is the ABS -but I've been told not to put ABS in a tank but I'm sure a few bits under sand wont' hurt anything.