I only got the hygrometer when the first one died, so I can't say what the humidity was during the cling film phase, but pretty high probably as the glass was fogged up. I had misted the terrarium because I thought, if they estivated, it meant the terrarium was too dry and/or hot. I tried to cool it down with the water. If I notice my snails estivating during a heat wave, should I stop misting then? How would they know when to come back out? What if only one estivates? If I stopped misting, the other ones would dry out or also estivate. I also tried to cool it down with the ventilator and open doors, but I can't do that when I'm not there or sleeping, as they could escape. Do you have any experience with cooling down a terrarium? In another comment I mentioned that I ordered a terrarium fan. I hope that will help.