HCA: Hermit Crab Association

Hello hermit crab friends....my son and I have 2 hermit crabs in a 29gal tank. We have live miss on the back wall, loose moss, and sand for the substrate. We also have 2 smaller heating pads one on the back and one on the side. We have a 100 watt heat bulb and a little humidifier. We cant seem to keep the temp above 40 or the humidity above 50. We spray the moss 3 times a day and let the humidifier run for about 3 hrs we also have been keeping the heat lamp on all day and night. I am at a loss and dont know what else to do. Any ideas? (I don't know how to upload a picture to show our terrarium)

Try covering the tank with plastic wrap so it traps all the moisture that would evaporate out.


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Heat lamps will zap humidity, especially since you are keeping it on 24 hours a day. I'd get larger, more efficient uth (under tank heaters). Make sure they are mounted above the substrate line. I don't use an uth since my temperature in the house is always warm, but someone on here can recommend the best brand for the job. From what I've read on here, Zoo Med uth aren't very good. You can also cover your tank top in plexiglass to help keep humidity in.

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Vzgreen wrote: ↑

Thu Dec 19, 2019 7:25 am

Hello hermit crab friends....my son and I have 2 hermit crabs in a 29gal tank. We have live miss on the back wall, loose moss, and sand for the substrate. We also have 2 smaller heating pads one on the back and one on the side. We have a 100 watt heat bulb and a little humidifier. We cant seem to keep the temp above 40 or the humidity above 50. We spray the moss 3 times a day and let the humidifier run for about 3 hrs we also have been keeping the heat lamp on all day and night. I am at a loss and dont know what else to do. Any ideas? (I don't know how to upload a picture to show our terrarium)

I'm a bit confused about your post. You have 2 smaller UTH and a 100W heat bulb on the tank and it still won't stay above 40 degrees? I hope that's a typo about what the temperature is!

I am relatively new to the world of hermit crab, but I can share with you my experience. We currently have a 10G tank for 2 crabs. In the beginning, I had terrible problems with heat and humidity. I bought a day/night heat lamp, but it was keeping it too warm and zapping the humidity. Something about the stark heat of the lamp dries out the air. The temperature was good, maybe a little too high, but I was constantly having to mist. I returned the heat lamp and got another UTH. So, I now have a 5-10 G rated UTH and a 20-40 G rated UTH both by Zoo Med and it keeps the temp between 75-80 constantly.

For humidity, I remade my substrate with a combination play sand and cocofibre. I sufficiently wetted the substrate before I put it in. The terrarium we have has a screen lid. I have a piece of plexiglass that I put over the screen and can adjust how much of the lid is covered by the plexiglass to keep the humidity around 80%.

In your case, what is the temperature range? Is it really 40 degrees Fahrenheit?

Hello and welcome to the HCA! Getting the heat/humidity right in the beginning is tough. You do not need to nor should you follow the zoo med recommendations for tank size. I'm linking the basic care guide, the heat sections speaks about it. I started with a 10 then a 20 long ,I currently have a 40 breeder and am building an aquarium stand for a 75 gallon. I put 1 large 16 watt zoomed on the back of the 10 gallon above the substrate on the 10 gallon and it kept heat ok. On the 20 I had 2 zoomeds of that size 1 that covered the short side and 1 on the back. Reptile basics makes a better quality product (probably cheaper too) and you just have to order it and wait for it to ship. Other places sell them but I found that ordering direct from reptile basic was the cheapest I could find. You tape it to the tank and it is a good idea to have the whole back of the tank covered. I ordered long ones for the back of both my 40 and 75 plus 2 for the sides. I don't know that I need 3 UTH per tank but I wanted to have them just to be sure, you can always unplug or set them up with a temperature control switch.

https://www.hermitcrabassociation.com/p ... 0&t=119273

https://www.reptilebasics.com/ultratherm-heat-pads

Yes it was really at 40 degrees. The bulb we had I don't think was a heat bulb just a light so We did end up getting a day heat bulb and a night heat bulb that are both 100 watts. Still over night the temp was low we even moved the lamp closer almost directly inside the tank. I am going to try to move the tank to another location in our house. We live in a basement so I think where they are at it is just colder in general. If moving them don't work I am really at a loss. Because those lights should be working to help keep the heat with the heating pads we have on the tank

Hi. Have you confirmed that your temp gauges are working properly? That would be my first thing if the room where the tank is kept is warmer than 40 degrees itself. With the heating pads and lights, it seems like it should be heating and maintaining better than that....hope you can figure out the culprit and get your crabs toasty again,

Depending on the brand of heat pad you have, some can be insulated to e sure heat stays in the tank. Zoomed can it be insulated, but ultratherm can. Of course, 5his is assuming that your gauge is working properly.

The care guides has a section for calibrating.

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I may be wrong, but zoomed can't be insulated since its already insulated out of the box. I believe flukers can however.

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I think Scarlet has a typo - Zoomed 'can it' be insulated - I think she meant 'can not' be insulated.

curlysister wrote:I think Scarlet has a typo - Zoomed 'can it' be insulated - I think she meant 'can not' be insulated.

Ah, yeah true... haha, was still before my morning coffee! ^_^

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Hah yeah, it 2as a typo. It was very late xD

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We re-homed a hermit crab in a 10 gallon tank. It has a ceramic heat lamp that keeps the temperature perfect but the humidity is terrible. I cannot keep it where it should be. I will be getting some moss as suggested and I put some saran wrap over the top (away from the heat lamp). I would like to get rid of the heat lamp but am not sure that the under the tank pads will be enough to heat him properly. Can someone tell my exactly what to buy? I think if I get rid of the heat lamp, my humidity levels will improve. I should also add that 2 days after re-homing he has buried himself and does not seem to be coming out at all. So I assume he is molting?

Try an Ultratherm heating pad from Fluker’s or Bean’s End. One large enough to cover the back of the tank should do, but you need to provide your own adhesive to attach it. HVAC tape works well.

And yes, digging and disappearing is normal and expected.


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LOL, this is the thread of typo's!
Joe, did you mean Bean Farm?