Plastic tub warping

[bcr229]

Just to be sure. You are not reading temp over substrate, right? Like bcr said, measure over heat tape at the tote's floor. That means you're moving the substrate to the side to reach the bottom plastic.

Good point. This also includes newspaper as substrate because if it's not weighted down you can get a very thin air gap between the paper and the tub floor, which means the paper will be cooler than the plastic.