Test terrarium - lessons learned and questions

[andy83]

Not as small as gravel but I've seen it the size of a bit smaller than your average marble. It usually comes in various sizes according to the manufacturer. But mostly the size of a marble I would say.

The smallest I've seen it was at a Petco I think but it's a ripoff there. You're better off getting it from a hydroponics store or the like. Some of the big hardware stores might even carry it.