I have a 40B with a cane toad (
Rhinella Marina) as well as 2 empty terrariums (10g, 20 long). I moved the empty terrariums to the very cold basement to dry out, and I replaced the substrate in the 40 with substrate that we baked in the oven at 400 degrees for 20 minutes. (Several small batches). I also plan to get a
sundew (Drosera Capensis) to combat any future hitchhikers hopefully before they can get established. We're moving to Arkansas soon, which is a lot buggier than NJ. I think baking the new substrate fixed it though! We haven't had any gnats since!