You could go with either round river stones or glass marbles. They won't be able to mover the river stones if they are large enough but it tends to trap allot of waste underneath them. With the glass marbles on the other hand, the fish will still be able to move em but they won't trap as much waste and with the completely round surface of em they won't scratch glass or acrilic.
As long as it's glass, it's safe. Glass won't leech any chemicals into the water. I used to use just regular shooting marbles that ppl buy for kids to play with, only reason I don't use em any more is because I wanted a more natural look so I went with sand instead.
www.the-crafts-outlet.com
Looks round and smooth enough to work. I'd definitely think of trying it atleast. Looks more natural the just random colored glass marbles.Been following along with the convo and did some digging. Do yall think these glass microbeads could work as a sand substitute thats acrylic safe?
Glass Microbeads, Caviar Opaque, 0.6mm, 1-oz, Black
1-oz/28-g Opaque Finish, Glass, Microbeads 0.6mm, Opaque Black
