Grout is the preferred medium for formicaria, with polyblend being a popular brand. I do not believe the polymer inside the grout will affect your results. It is important to note that unsanded grout absorbs water better than sanded, and when mixed with perlite, is a good medium to make sections of your formicarium more absorbent to help create more or less humidity depending on your needs.
Crystal has a great guide here that you can borrow tips and tricks from:
http://www.formicult...icture +journey
Edited by CallMeCraven, November 18 2016 - 3:18 PM.
Current Colony:
4x Camponotus (hyatti?)
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Harmony with land is like harmony with a friend; you cannot cherish his right hand and chop off his left.
-Aldo Leopold