Q and A: Is charcoal neccesary for terrariums?

Thanks to Valerie for a new Q and A.

Question: Will I be ok without the charcoal since they are open terrariums?

Answer: An open-top terrarium should be fine without charcoal but if it starts to smell noticeably swampy I would dump it out and try again. Once a terrarium starts to stink it won't stop on its own and will most likely only get worse- especially if any critters hitched a ride into the terrarium and then find themselves deceased. Charcoal acts as a filtration system for decaying matter in the enclosed terrarium system (enclosed meaning no complete vertical drainage).