Hi, I have two spiders, an adult Chilean rose and a pink toe sub adult, and I have just upgraded there enclosures but I am having a hard time heating them. I have always had a hard time heating the chiliean. I have 12" x 12" x 12" Exo Terra Terrariums with 1 inch of substrate, the coco stuff. For each enclosure I have a 11" x 5" 7W heat mat heating half of each. But the temperatures never get above 20°C and I am aware it needs to be around 25 - 28°C for both with the pink toe being sprayed and kept damp (75 - 80% humid) and the chilean being a bit dryer (50 - 60%). I have mounted the mats on the side and on the underneath with the same results. Could anyone give me any tips on how to get them warmer? Thanks.