HCA: Hermit Crab Association

My tank is currently sitting at 90 and goes into the mid to upper 80's overnight. Is 90 too hot? The humidity stays in the upper 80's.

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In my experience, when temps get to the mid-90s or higher (and by this I mean throughout the whole enclosure. No cooler spots.), my PPs are all hanging out of their shells acting overheated. But, as long as there are areas within their enclosure that are cooler, they're fine. 90F, especially with some cooler areas, shouldn't be a problem.

Yeah I have a cooler areas. The 90 degree area is near the heater. I did notice they were still moving around in the crabitat and they managed to trash the place so I guess they were good lol.

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Last bad heat wave we had, mine had no trouble with temps up to 95, but it was cooling off 15-20 degrees at night so it wasn't constant. I regularly have crabs sit directly under the bulb where it's over 100, and they seem to like it. I figure it's a lot like sitting out in full sun in the middle of a beach. They have the option to move away and cool down whenever they want.

wodesorel wrote:Last bad heat wave we had, mine had no trouble with temps up to 95, but it was cooling off 15-20 degrees at night so it wasn't constant. I regularly have crabs sit directly under the bulb where it's over 100, and they seem to like it. I figure it's a lot like sitting out in full sun in the middle of a beach. They have the option to move away and cool down whenever they want.

Right. They will also dig into the cooler sub if the air is too warm for their liking. Your substrate should always be cooler than the air anyway. Think of it as if you were digging your hand down into the sand on the beach; it gets cold a few inches down.

No part of the tank should be able to ever be colder than room temperature - even the substrate - so if the room is also hot, that is going to be the lowest temperature point. In practice though, evaporation can in some cases lower the temp ever so slightly, but it's rare. It can also take time to heat or cool a thermal mass, so the substrate will often be a few degrees behind whatever temperature change occurred, for at least a few hours,

wodesorel wrote:No part of the tank should be able to ever be colder than room temperature - even the substrate - so if the room is also hot, that is going to be the lowest temperature point. In practice though, evaporation can in some cases lower the temp ever so slightly, but it's rare. It can also take time to heat or cool a thermal mass, so the substrate will often be a few degrees behind whatever temperature change occurred, for at least a few hours,

Sorry I meant that the sub should be cooler than the air in the tank but not refrigerator cold.

I agree with you both, so long as there's cooler areas. The few times my house got really hot and I forgot to unplug the heat source, temps in the tank being mid-90s and higher throughout, all my PPs on the surface were hanging out of their shells acting overheated. But most of the time, even with very hot areas (like you describe Wode, closer to the heat source) they've been just fine as long as there were cooler areas to move to if needed. I've seen them bask too but always with the ability to move away when they needed. Sorry if my first post was not clear.

I do however usually unplug my heat source come summer. Even without it, temps stay well into the 80s in there.

I do the same! In another month we'll be heater free until the start of September, if everything is the same as the last few years.

Thank you all for your replies! My house is about 76 right now with our AC going. Wode I can unplug the heater in the summer? My house gets hot even with the air on.

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Sorry if it seems like a silly question this is my first summer with my babies!

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You may need to, if it gets too warm! Or at the very least dial it back to where it's not going to overheat. UTHs and heat bulbs are indiscriminate abount how much heat they put out, unless they are hooked up to a thermostat. 20 degrees of heating will always be 20 degrees, whether that makes the tank 80 degrees or 100 degrees.