It doesn't say anywhere on its data sheet that it's potable. For that reason I would not put it long term in a fish tank.
Also the styrofoam backgrounds are surprisingly easy to make. I made two myself recently. I got styrofoam from Lowes ($13), Great Stuff foam from Lowes (three or four cans, $12), some gravel (you can get it for $5 a bag at Home Depot or etc hardware store). A can of silicone ($8, local pet store) so you can attach the styrofoam to the glass aquarium wall. You might want two tubes so you can patch up holes in the foam where rocks fell off.
I cut a garbage bag down its side and spread it out flat for my work area. It was easy to simply lift off and up and into the trash, cleaning up in one fell swoop.
Here's a link to where I documented the build: http://forum.aquatic-gardeners.org/view ... 9&start=90
Yes my rock is fancy expensive foreign country rock no I wouldn't buy it if given a second chance and yes the $5 bag of marble chips or lava foam-rock from the local hardware store would work just as well.
Close up photos of top tank (there are two stacked one on top of another): http://forum.aquatic-gardeners.org/down ... php?id=441http://forum.aquatic-gardeners.org/down ... php?id=440
I built the bottom tank to have custom tank dividers in it to separate fry of different sizes as they grow: http://forum.aquatic-gardeners.org/down ... php?id=425
Yeah, it was easy. And cheap. And potable. This is a no-water-change tank setup so I couldn't have poisons slowly leaching out into the water.