Humidity issues

[Lexi0Black]

I have had my hermit crabs for 3 months and am struggling with keeping the humidity up. I have a mixture of substrate and play sand, with Moss, and a salt water bowl and fresh water bowl. The top is a metal crate that I have sealed 3/4 of the way with acrylic sheet. The 1/4 that is uncovered has a 40 watt lamp on it. If I go use a heat lamp that is any lower my temp drops too low. I mist my crabs at least twice a day and soak the moss once every other day. What am I doing wrong with the humidity levels?

[curlysister]

A couple of things come to mind.
First, have you calibrated your hygrometer? Even if it's new, it may not be accurate. We have a care sheet that explains how to do this.
Second, could you use a heat mat on the back of the tank instead of a heat lamp? While some people do use heat lamps successfully, they are known to zap humidity. Some climates are obviously better suited to heat lamps than others - I live on the Canadian prairies LOL.
Lastly, how big is your tank and how deep is your substrate?

[Lexi0Black]

To answer your questions in order.
Yes I have calibrated my hygrometer.
I unfortunately do have to use a heat lamp but I am also using a heat mat at the back of the tank. This is the only way I can keep the tank at a livable temp. Even with those things, I am ranging between 50-60°F but no higher.
I have a 10 gallon tank with 6 inches of substrate/sand mixture with another 1.5-2 inches of moss in certain areas of the tank.

[curlysister]

Have you considered insulating your tank? Not all UTH's can be insulated over top, but you can insulate around where the UTH is. And the portion of the tank without the light. Even using cardboard wrapped in tinfoil will helf reflect heat back into the tank.