Thanks for the reply!
I bought the substrate as it stated on the bag that it was recommended for amphibians (it's called forest floor bedding, and is 100% natural cypress mulch). When I opened it I thought it looked way too prickly, but as it cost a lot of money and says recommended for amphibians, I went with it. I do have a water bowl, which the frogs do use. The thermometer is a brand new one, I only got it 5 days ago so I'm peeved that it doesn't work..
Also, I spray the terrarium twice a day all over. The substrate feels damp to the touch.
Arrrrrrrrrrrgghh! I was doing sooooo well with the baby frogs, these adults are far more stressful lol
I'll go to my local pet store tomorrow for a different substrate!!