I have a 20 Gallon Bioactive Vivarium that is currently still settling in. I set it up on June 17th and plan on adding my toads on August 17th. The substrate is an ABG mix. I have springtails and Dwarf Purple Isopods in there now. There are also live plants. Would it be ok to mix some sand into the substrate? I have fowlers toads and I think they would prefer a sandier substrate.