I am using gravel as a drainage layer with mesh over that and then ecoearth. I have heat pad on the side and have a cutout in the tinfoil for a 5.0 uvb which i recently just added because I'm adding a pothos since she's too big for solid hides. I replace substrate about every month and a half. I mix around the substrate when ever it looks all flat and really packed down. It is white mold but doesn't really seem to go away it just grows. I do scoop it out then i let the thin top layer of ecoearth dry out.