HCA: Hermit Crab Association

I'm starting to wonder if our thermometer is accurate and I'm getting frustrated because I'm having so much trouble keeping temps in the tank where they need to be. We have 2 PetSmart thermometers, one on each side of the tank, and a national geographic hydrometer/thermometer that sits outside of the tank but has sensors inside the tank. The 2 petsmart thermometers pretty much always read just over 80 (~81 on the left side and ~83ish on the right side) but the national geographic one has been reaching 80 around mid-afternoon but mostly sits around 77ish the rest of the day. First thing in the morning it reads extremely low, though.
Anyone else have experience with the national geographic hydro-thermometer? Also, any recommendations on thermometers that are definitely accurate? I know the hydrometer part is fine-- I've calibrated it and all. But I don't have thermometers other than the petsmart ones to compare the nat geo temp to, and I'm not sure how accurate those are either.

If you find an awesome one let me know. I'm on my 4th gauge since October. I don't think they construct these things worth a darn.

The one I got from reptile basics is pretty awesome.

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Raw, you bought that one about a month ago or so, right? It's still holding up? I have not had one last that long yet.

This is what I'm using now: http://m.lowes.com/pd/AcuRite-Digital-W ... or/1075631. Of course any brand, digital or analog, can be off - both the thermometer or hygrometer. So far I really like this one.

It seems to be doing well. I keep the probe in the tank, but the display out on top. (I'm hoping to help prolong its life) Pretty consistent readings so far. Temp does read a few degrees high though compared to the plain Jane old fashioned thermometer in my house, but I just mentally adjust. Hasn't made a huge difference either way. The feature I like best is the fact that I can reset the low and high every couple of days so I know how much the environment is fluctuating.

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Speaking of tank gauges, my crabs have a habit of trying to climb on them and they pull them off the glass, (held on by velcro that is on the glass and guage) they have pulled the sticky velcro off the glass so now the Substrate is all over the sticky and won't stick. Anyone else use velcro for their guages.

When I started I went on the hunt for small sized gauges, here's a thread on what I'm currently using:
viewtopic.php?f=26&t=110351

For temp only, I really like the small accurite that suction cups to the glass. It's made for windows so you can flip the suction cup around for the thermometer to face in either direction. For around $6, it has min/max temp, too! Wish they made an equivalent hygro! My Lowe's carries an updated version and links are in the thread above.


I've since moved it to the 20g, directly under a corner shelf (that's where the facing out feature is handy) so the crabs can't climb on it anymore (at least, so far it hasn't been knocked off!).

Candie wrote:Speaking of tank gauges, my crabs have a habit of trying to climb on them and they pull them off the glass, (held on by velcro that is on the glass and guage) they have pulled the sticky velcro off the glass so now the Substrate is all over the sticky and won't stick. Anyone else use velcro for their guages.

There's a thread somewhere that suggested attaching gauges to popsicle sticks or wooden skewers and just sticking them in the sub. Easy to relocate them. I have one suction cup thermometer but the rest of my gauges are on sticks. I have one velcro gauge that I'm not using because of the unsticky-sticky problem, I'm considering just attaching it directly to the glass with a command strip, those have held up really well in my tanks.

This is the one @Rawrgeous and a few other crabbers have -- it's the next one I'll be ordering as I've had it with the Acurites.

http://www.reptilebasics.com/thermometers/TH-100/

Thanks for the responses, guys! I'll check out your suggestions and see what I can do. The sensors on ours suction cup onto the glass (or just kinda dangle sometimes haha) and the display sits on top, as well. I think I'll try the Popsicle stick idea, too. It may just be that the tank doesn't stay warm enough and I'll have to figure out a way to add more insulation and tweak some things. It seems like most people use a UTH or 2 and insulate them and they're good to go-- I want ours to work that well, too lol. They don't seem to be having any issues but I know 69-71 is way too low and I feel awful if that's accurate.
I'll throw a blanket over the top, sides, and back at the very least and see if that changes anything. Only thing I'm unsure about is if it's safe to cover the light-- and I don't wanna turn it off because it seems to help raise the temps during the day.

Actually now that I think about it.. If those low temps really are accurate that would mean it was same temp inside the tank as it was in the house-- on colder mornings the house temp has read 68 when it's set at 70, but it's noticeably warmer when you stick your hand in the tank. So that makes me think something almost has to be wrong with it.

I like these:

http://m.lowes.com/pd/AcuRite-Digital-W ... on/3830957

I stick a chopstick up into the hole on the back, and then set them around the tank in the substrate. I have two in my 90g and one in the 10g iso. I also have smaller temp and humidity gauges on sticks or bits of plexi (that was me that posted that idea about gauges on sticks, it's been a lifesaver--literally--for us). Temp and humidity is so essential for crabs I always have multiples so I can cross-check (even if they've been calibrated, things can go kaflooey with them). Having them on sticks instead of stuck to a tank wall allows you to quickly set up an iso with some gauges you know are working properly, if necessary.

I really think that putting them on the tank sides is not the best thing, anyway. The glass can conduct heat, so you aren't really getting an accurate read of what the ambient temperature is inside your tank, but something influenced by whatever the air temp is in your house as well, and water vapor often condenses on the glass, so the humidity is likely to read higher right there than it really is in the ambient air in the tank. Being able to stick your gauges in the substrate here and there throughout the tank gives a much better read of what the conditions are where the crabs actually spend time. Further, you can move them when you like, so you can check different areas, and they don't have to limit your decor options, either (once you stick them to the tank wall, you're "stuck," pretty literally--you can't put a UTH there, you can't put a climbing wall there, you can't put climbing apparatus too close or they'll pull them off the wall, etc., etc.).

Using chopsticks and putting them in places where they aren't right next to climbing apparatus, I don't find the crabs climb on the gauges at all (I think a chopstick is too narrow for them to think it is a branch to climb on). And those Acurite gauges just happen to be at a great angle to read from the top of a tank, with a chopstick stuck up into their "hanging hole" on the back. They aren't super cheap, but they aren't crazy expensive, either. So far (I've been using them since before Christmas), they've been working great.

DragonsFly wrote:I like these:

http://m.lowes.com/pd/AcuRite-Digital-W ... on/3830957

I stick a chopstick up into the hole on the back, and then set them around the tank in the substrate. I have two in my 90g and one in the 10g iso. I also have smaller temp and humidity gauges on sticks or bits of plexi (that was me that posted that idea about gauges on sticks, it's been a lifesaver--literally--for us). Temp and humidity is so essential for crabs I always have multiples so I can cross-check (even if they've been calibrated, things can go kaflooey with them). Having them on sticks instead of stuck to a tank wall allows you to quickly set up an iso with some gauges you know are working properly, if necessary.

Ah, that was you! That was brilliant. I like to keep my options open so this really works for me.

That gauge looks like it would be easy to read in dim light, since it's black on a white background. What are the dimensions of the unit? The specs say about 3"x3", but don't give the thickness/depth (front to back). Plus I've had problems with online specs giving the dimensions of the packaging v. the actual item.

The 3" x3" estimate is good with respect to width and height; they are an irregular shape front to back, so it's hard to say; I don't think they are any "deeper" than about 2" to the "deepest" point. I have one stuck on a chopstick (broken off, so it's not too tall) in my 10g iso, it's big for that tiny tank, but since it's an iso, who cares (I have about 6 other gauges here and there throughout that little tank, too, because I was paranoid about conditions for the poor crab that is in there; he went mostly "naked" for several days before I could get him to stay in a shell). I have two of these gauges at this time in the 90g (plus some other little ones on sticks here and there); I would like a third one in the 90g, because they are so easy to read, and right now I don't have one of this type on the "beach end" (because I took the "beach" one to use in the iso). If I do want to check them at night, I do have to use a tiny light to read them--but my night vision is not what it used to be; the young'uns with better rod function might be able to read them fine without assistance.