Have a "knockdown" terrarium, made for reptiles, and went to glue the back ground in after using it all winter to keep a nice ambient temp for my stimmy in his click-clack, and the base had some nasty cracks all through it, starting in one spot and spreading all through the base.
I had a 7m heat cord on a marine ply board, on a thermostat, set for 23 degrees. I suspect that while I was testing it, and had it set for 30, there was too much substrate, because when I scraped it all away, I was measuring 70 degrees!!
Anyway, lesson learnt, minimal substrate, otherwise it will crank up the heat trying to get up to temp, and cause all sorts of issues.
Taking it back today to get a repair, can't really ask for warranty replacement when there are melt marks on the bottom.
Anyone else learnt the hard way??