Notice I didn't say thickening the substrate layer is IDEAL, and I also suggested using the travel carrier pictured in her other post to prevent digging down to an unsafe heater. Incidentally, thicker substrate isn't necessarily going to result in hotter glass. Depending on the substrate, it may even dissipate some of the heat. That's the reason there are different UTH's for sand vs "bedding" substrates. Considering that she appears to be using coconut husk, there's a lot of dissipation going on. Coco husk is one of the least conductive substrates.
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