Well I'm mixing up water for a water change and I decided to do 2 brute containers worth (I should have kept the 2nd 100g tank, that would be an ideal amount ). And part of the larger than normal (for me) is I'm going to start siphoning refugium sand out. I really like the way Kris does his refugium, which looks like a bunch of rock rubble (need to ask him again) but that seems like something that can easily be siphoned out, where as with sand you're almost guaranteed to siphon just as much sand out as you do crap. He replaces his sand quite often though. Corals will encrust to acrylic bottoms. I had a lepastrea form a puddle that was easily 6 inches wide on my bottom once. And I've also had green slimer encrust and branch (if you don't like the flatness... remember though flatness allows detritus to move and settle in dead spots a lot easier so you have target areas to siphon!) If you have time check out Rich Ross' tank thread, he did a textured bottom with sand and epoxy IIRC. It looked great at the beginning but like everything eventually became coraline covered. But if it's just a texture, then go for it.