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New here! Hygrometer calibration question

Posted: Thu May 21, 2020 8:51 am
by HermieCrabs
Hi, we are brand new here! And pretty new at hermit crab stewardship too, but trying really hard to get everything right. This is our first post.

We have two analog hygrometers in the tank currently but they vary widely on their measurements. For instance right now one says 82% and one says 85%, but last night they were further apart. I think one may just be more sensitive than the other.

I am adding a digital Acurite thermometer/hygrometer to our setup, to try to get a more precise reading. Last night I put it in a sealed food storage container with a shot glass half-full of wet salt. But this morning it was only at 65% after about twelve hours. So I've moved it to a ziplock bag instead; the percentage dipped down into the 50s and is now climbing back into the 60s again. I'll leave it all day to see what happens.

So my question is - what percentage do your own digital hygrometers deviate? Is this salt test really reliable? And how much difference do you all regularly take into account, before you just throw up your hands and try something else?

Re: New here! Hygrometer calibration question

Posted: Thu May 21, 2020 1:02 pm
by JoeHermits
My last one read eight percent too high for two years before I replaced it. I got a new humidistat instead of a regular hygrometer that reads four percent too high.

Since hygrometers are fairly prone to breaking down I try to calibrate mine about once a month.


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Re: New here! Hygrometer calibration question

Posted: Fri May 22, 2020 3:16 pm
by GotButterflies
I've been fortunate enough to have accurate ones. I use the Accurite ones. I don't use storage containers. I do a ziplock bag to check mine. Accurite does have several different kinds - I go for the cheap one. They used to be $8 - Now they are $11
https://smile.amazon.com/AcuRite-00325- ... 184&sr=8-2

Re: New here! Hygrometer calibration question

Posted: Fri May 22, 2020 6:59 pm
by CrabbyLover77
I put my hygrometer and salt inside 2 ziplocks to make sure it's as airtight as possible. I give it 24 hours before I decide to finish calibrating. My one meter was a couple percent off, but I was able to manually calibrate it (it had a button to move the % up or down). My other meter is 2% too low. But both of my meters tend to read at 99% anyway.

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Re: New here! Hygrometer calibration question

Posted: Mon May 25, 2020 4:43 pm
by HermieCrabs
Thank you all! I have it in the tank now and it seems to be responding well and consistently... maybe I just didn't do the salt test accurately! I never got it to budge that way. But the crabs seem happy in there, and the hygrometer seems quite sensitive and responsive... fingers crossed it holds up!