Added heat, losing humidity?

[NewHermieFam]

I'm new to having hermies and the first 2 weeks in our 10 gallon tank, I had no problems with humidity (usually between 75-82). I had a small size side heater that only bumped the tank 2 degrees to about 74. After research this didn't seem warm enough so yesterday I added a medium heater to the back of the tank and now the humidity keeps plummeting!! The med heater bumps the tank another 3 degrees to about 77-78. That doesn't seem too hot but my humidity keeps dropping to 60 or as low as 50! I keep spraying, I have sponges in the fresh non-chlorinated water (which seemed to work like a charm before) and now have added natural moss and am spraying that too! What am I doing wrong? Is the 2nd heater too much?
Thank you for any help!!
-Amanda
New Mom to Elliott, now molting Addison & freshly molted Sabastian

[NewHermieFam]

I have pictures if I can figure out how to add them... Maybe on PC. Right now 80 degrees, 60% humidity and wet in there! And I sprayed again!:( frustrated

[NewHermieFam]

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[emmac350]

You have run into the laws of physics/meteorology, I'm afraid. Let's see. Humidity is a measure of how much moisture is in the air compared to how much moisture the air could hold. The warmer your air is, the more water it can hold. So while the amount of actual water vapor in your air is the same, if the air temperature is higher your humidity level will be lower.

Let's say your tank has (I'm making these numbers up for the sake of illustration) 75% humidity and the temperature is 75 degrees. At 75 degrees, the air can hold a maximum of 4 units of water; because the air has 3 units of water, you're at 75% humidity.

Raise the air temperature to 80 degrees. Here, the air can hold 5 units of water maximum; however, you haven't changed the actual AMOUNT of water in the air so you still have 3 units. So at 80 degrees you have 3 units of water out of a maximum of 5, or 60% humidity. If the temperature goes back down to 75, your humidity will go back up to 75%, though the amount of water is still the same.

Those numbers are totally made up but it lets you see why your humidity drops when the temperature raises unless you do something to raise it. If your heating element is only on for a little while it shouldn't be a problem (I run into this with my heat lamp when the thermostat turns it on). If your heater is on all the time you'll need to find a new way to raise the humidity level (could you put a bowl of water right by the heater so it evaporates?

[NewHermieFam]

Thank you so much for your response and it's exactly what I'm finding. I moved the larger of the 2 side mount heaters by the fresh wAter with sponge and also added moss to that side. I find when both heaters are on, I get up to 80 degrees but humidity wants to constantly drop to about 60%. I'm constantly spraying & pretty much soaking my entire tank to get the humidity up to 80% for a very short time. However when I unplug the smaller heater, my temp drops to about 75 but humidity stays up longer.
I will keep experimenting with keeping humidity up because as far as I've read, 80 degrees is better than 75, right? Or are my hermies ok at 75 degrees? Whether the tank is 75 or 80 degrees, my hermies typically find their way to sleep in the moss against the heater side.
Thank you for taking the time to help me!

[emmac350]

75 is okay, but upper 70s to right around 80 would be perfect (at least that's where my crabs seem happiest). However, the most important thing is having a good temperature/humidity combination so if 75 means you have good humidity consistently, go with that.

Just a thought - where is your humidity gauge? If it's high in the air, remember that the crabs are down at the surface. There is a considerable difference in the humidity when you move around in a tank, especially if there are a lot of ornaments in the tank. Before you're sure that you need to constantly mist, see if moving your gauge to where the crabs are gives you a different reading.