What can I put under a thin sandbed to hide the glass?

[Tired]

I want to have a thin sandbed in my upcoming tank, about 1/2", so I can have the look of sand without needing to worry about gunk building up in there. Trouble is, at that depth, it's easy for flow or a digging critter to dig right down to the glass. That doesn't look great. 

 

What can I put under the sandbed to make it look reasonably decent when the floor is inevitably uncovered? I'm getting a coarse, shell-bit-filled type of sand from Tampa Bay Saltwater, so I need something textured to put under it. I know some people use travertine, but I've seen discussion about it potentially being contaminated, or releasing things like aluminum into the water. So what else is there? 

 

Can I just buy a big sheet of the stuff frag discs are made of? I know it'd shatter in shipping, but I do have glue. 

[LazyFish]

If you are able to I've seen people put things under the tank itself if it's a rimed tank it works well if you can find something with color of sand and it helps it not be so obvious when theres bald spots. Perhaps vinyl.

I've also seen PVC or vinyl sheets like for cutting boards put under rock structures. Maby you can find a piece and cut to size? Maby leave a small gap so actual sand could settle there and not be as obvious at the edges.

[debbeach13]

Paint the outside bottom of the tank before you put it on the stand 

[Tired]

Oo, looks like I can get ABS plastic (Lego plastic) in white, with a textured surface. That should work. Might stack a few sheets to get a little extra height, with silicone along the edges so there aren't any crevices between them for detritus to get into. Should probably also silicone it to the floor of the tank. If I hate it, I can peel it out. 

 

I'll definitely leave a small gap around the edges, just big enough for a cerith snail to comfortably fit in and out. Partly for appearance, partly so my ceriths can vanish a bit more if they want. I'm going to make sure to have enough sand for them to bury in, though that doesn't take much. The sand is also so I can keep a candycane pistol shrimp, but since those are tiny, they're fine with half an inch of sand. They mound it up deeper around wherever they live anyway.