HOW are yall keeping your humidity in a normal range in winter?

We have our girl in a PVC enclosure. 4 inches of substrate, a mix of coco chip, coco coir and spaghnum moss. Water poured into all 4 corners. The enclosure is solid topped, not mesh.

During the summer it’s fine. We live in Georgia and are in a cold spell right now, so the room that all our reptiles are in has a space heater going, because it is just so cold in our house. I can’t get the humidity up past 30.