Is humidity variance normal?

[junebug]

I'm having some weirdness with the vivarium I set up this morning. I've been watching the humidity, as I'm going to be adding bumble bee toads to it after their QT, and the humidity is a bit too high at 75%. Now today it's a bit sticky where I live, so this might be part of it. I don't have AC so whatever it is outside, it's usually the same inside.

However, on a whim, I removed the hygrometer and held it in another spot in the tank, actually right over the bathing pool, at the very top. Right now it's back on its' velcro hook behind the wood and among the plants. But when I held it over what I had intended to be the "wettest" part of the vivarium, the humidity dropped. Like 5-6%.

I'm weirded out by this. I planted the tank so that the grasses growing out of the bathing pool would (hopefully) create humid pockets, as I expected the tank to be a bit on the dry side. So frankly I'm concerned about my toads' health.

[LilyPad]

What hygrometer are you using? They are notoriously inaccurate. I've been most successful with the nat geo hygro/thermometer so far. I usually have 2 in my tanks at all times to try to get the best idea of what is going on. So each of them have a nat geo and exo terra at the moment. The exo terras gives me a constant reading of 99% while nat geo seems to be more on.

[DigitalPunk]

Amy is right. Hydrometers are wildly inaccurate. At the best of times they give us a vague idea what the humidity is + or - 10%. Analog Hydrometers are garbage. Get the digital one Amy recomended or try the exo terra Hydrometer. I actually use Glass aquarium thermometers for temp readings in all my tanks now. So much more accurate lol.

[LilyPad]

Is this your first viv? Once you have some experience, you'll easily be able to tell if humidity is in an appropriate range by the plants, glass, and smell.

[junebug]

Yes, it's my first viv. I don't have a digital one since I don't have anywhere to plug it in near the tank. The tank sits on a rolling butcher block in my kitchen lol. This particular combo thermometer/hygrometer is from ZooMed. I will look into the ExoTerra ones. This is just what they had in stock when I was at the store. I will probably pick up something better on my next visit to LLLReptile.

This is a link to the exact dual thermometer/hygrometer I have: Zoo Med Economy Dual Analog Thermometer/Humidity Gauge

I have a lot of substrate in the tank, due to the live plants. I guess it's very possible the peat/sphagnum moss is holding in enough moisture to cause the humidity rise at the back of the tank, since there is more peat back there to hold the rooted plants in place.

I checked it about 20 minutes ago when I came home from the boyfriend's house. It read 76% humidity. Just a few minutes ago, I checked it again and it read 82% lol. I wonder if it's just busted. The thermometer on it is working perfectly.

Edit: Oh. I think I found the problem LOL. It's 73% humidity in my town at this very moment. That's unusually high for us. I'm betting it's messing with the already not terribly accurate gauge.

[Mentat]

Just to let you know, the ET and NG hygrometers or combo gauges use small batteries and do not need electrical connections .