Humidity Problems, lost one crab already.

[wodesorel]

You can cover the entire back safely, but you have to watch closely for dry substrate near the pad. I need a full back one on my Teeny Tank to keep it warm enough. Others can get away with pads that sit above the substrate line. For even heating, you should try for something that covers side to side, even if it's only the top half.

[CrabbyHermit]

I'm confused. I was told not too far down past the substrate or it can burn them when they molt?

Also if you do not see where a crab dug how do you know where to avoid and keep them protected from others? I have two water bottles overt two but the other two I only have a general idea where they are.

Also I read they ate prone to die after purchasing them until they molt. So the ones molting now after this they 'should' be ok right? Or does this molt not count?

Sorry for all the questions, so many thoughts running through my head!

[wodesorel]

As long as you're not changing the temp once they are down, they won't burn themselves. They'll decide how close or far they want to be. If they are already down and close to where the pad will be (within a few inches), that gets dangerous since they won't be able to move away until they are done molting.

Even if you see where they dig down, they don't stay there. They'll end up on the other side of the tank many times. Under normal circumstances - not overcrowded with a proper amount and kind of substrate - there is usually no need to do anything special when they molt.

One molt is normally enough to get them out of the woods. Cold damage (being shipped without heating in winter to a home or a store) can sometimes hit after two or three molts, unfortunately.

[CrabbyHermit]

Well this is frustrating. I do need to up it by 10 degrees. I had it at a good temp but I lost it and don't know where a couple crabs are... so not sure what to do now.

[Bonk]

I'm guessing in this situation you would need to raise the temp slowly (because that's quite a lot of heat to add!). But unless you have a thermostat, I'm not sure how you would do this... OR you could wait until the majority of crabs were up OR (this may need double checking), you could assume that they're not too close. I mean, my crabs are always reluctant to bury beside the glass, probably because of the light. Also, mine are always at the very bottom of the tank. So if you could make the assumption that your crabs were at the very bottom of the tank towards the centre somewhere based on observations, you may be able to safely put on the mat.
Sorry for the long spiel, I was brainstorming while typing.