HCA: Hermit Crab Association

I have been having a few humidity problems lately... I have a Exo Terra hygrometer... how do i re calibrate it??? it didn't have any instructions on the package!!!! i should be having plenty of humidity so i don't get it any help would be appreciated...... it always says 50%

Mrs. G

look over here ---------------> at the crab care FAQ, it should give you the information you need.

i too am having trouble calibrating the hygrometer .... i've done it with this one at least 3 times and never get the same result, using different "airtight containers" one it's too high, one it's too low ... the other, dont remember but it sure wasnt 75% ... now also, you cannot reposition the arm of this thing .... nor the last one i had, that i dont understand when reading the instructions on the FAQ over here ----------------------->

both of mine didnt/dont have a "gear" like thing that you can turn to adjust .... they just kinda go "boooiiinnnng" when i try to adjust it any way

after a few hours of being in the container with the salt..a hydro should read 75% if it read 80% it is 5 high off or if it says 70% it is 5 low etc. you will have to just to the math...i had to.....because i couldn't adjust mine either. i finally gave up a bought a digital one.

does that mean you dont have to calibrate a digital one?

also, which one should i use the one way high or the one way low? like i said i've done it mulitple times with the same hygrometer and get different results

i guess i should just do it again? and use a ziplock bag (or 2 doubled up) this time to make double extra sure it's airtight?

I've gotten consistent results using doubled zip lock baggies. Also make sure you don't saturate the salt. Just about three to four drops of water is enough, if your using a soda bottle top.

My digital hygrometer has a button on it that I can hold down and it resets to 75% while it's still in the baggie. It's pretty fool proof. It's a xicar cigar hygrometer and since the first time I calibrated it, it has stayed very accurate, I haven't had to reset it. I just bought a second one to have for the cool side of the tank.

I did have one flukers hydrometer that always gave me way off readings that were never the same twice. I threw it away. I just couldn't trust it.

ok ... about 20 min ago or so i doubled up 2 ziplock quart sized freezer bags and we'll see how that turns out .... i'll check back about 4 or so ...

shellmybell15 wrote:does that mean you dont have to calibrate a digital one?

also, which one should i use the one way high or the one way low? like i said i've done it mulitple times with the same hygrometer and get different results

i guess i should just do it again? and use a ziplock bag (or 2 doubled up) this time to make double extra sure it's airtight?

it doesn,t really matter which one you use as long as you know if it is on the high side or the low side. if it was in the container for 6hrs with the salt and doesn,t read 75% exactly, then you know it is off.

for example if it reads 70% after the 6hrs then you know it is 5% off, so in the tat if it reads 75% then you know it is only 70% and the same if it is 5% high, if it reads 75% in the tat then you know it is actually 80%
and so on. It could be 10% off 15% off and so forth. you just have to know what % it was at when you calibrated it and then go from there.


all of mine read something different, i just used the one that was the closes to the 75% mark.

ok, it's been about 4-1/2 hours, i really think it's about 3% pts off ... it's reading 78% .... ok, so now i know ............... until that is i get that zilla digital one, but it's $20 so, not sure when that's gonna be ...

3% off is not bad. The one I threw away would read 30% during one time I calibrated it and then the next time it would read 90% and it would do the same thing in the tank. Jumped all over the place. I didn't trust it.

I will say that I picked up a window thermometer/hydro meter with a suction cup on it from Home Depot for $7.00 that is only 3% points off and its been a good hygrometer for me. I like it as much as I like the more expensive ones. It just can't be adjusted.

OK so I know this is a old thread but I wanted to say for the salt test to be accurate you MUST leave it in the airtight container (or ziplock) for the FULL 6 hours....just a fyi if you want a correct reading.

so i got myself a digital thermometer -hygrometer, the one with the remote sensor probes so i can read it outside the tank anyway .... i am "calibrating" it right now and in the same ziplock bag i have my original analog thermometer-hygrometer so i can see the diff btwn the 2.

so i started this 2 hours ago and what i have found interesting when occasionally checking is that when the analog hygrometer goes up the digital reading goes down ... hmmmm??????

while the temp on both machines are the same (69 degrees F) the humidity is way diff ... the digital is reading 60% and the analog is reading 84%

i have a feeling im still going to have probs reading the humidity.

i figured i was gonna have probs and i was right .... looking again at the calibrating hygrometer info it only states i"analog" however i put both my digital and my analog in the ziplock bag (doubled up) and really neither one changed that much since i placed in the bag oh 6 hours ago right now they are reading 60% on digital and 80% on analog .... wth did i do wrong? did i not get my salt wet enuff or too wet?