heating issue- too cold on one side

[graceisungraceful]

hi. so i purchased a 20 gallons tank for my new hermit crabs. i got this https://www.amazon.com/dp/B0002AQCL4/re ... =UTF8&th=1 12 x 8 undertank heater and placed it partially under, partially on the side of my tank at the recommendation of the girl at the store. i measured the temperature directly above where the heater is and got 83 degrees, which i know is great. i then measured the middle of the tank. 76 degrees, which is a little bit concerning, but seems alright. then i measured the side opposite the heater, and its a whopping 72 degrees, which is slightly higher than my houses room temp (70). im very concerned bc one of my crabs is molting on the cold side. my other crab sleeps on the warm side during the day but doesn't seem to stick to that area when shes awake at night. it doesn't seem like they are cold, but im concerned by the ten degree difference. 72 seems unacceptable to me. advice?

[LadyJinglyJones]

Oooohhhh.... did you place the heater under the tank, on the bottom?

If so, you want to change that as fast as humanly possible!
UTH heaters are designed as reptile basking heaters, heating from below like a hot rock.

But that isn't how crabbers use them. Instead, we use them to heat the air in the tank, placing them on the side, above the sand.

Because the sand has to be deep - at least six inches, right, and deeper is much better - the heater will overheat if placed underneath all that sand. Then it becomes both a fire hazard & a danger to your crabs - they can be cooked from below when they try to burrow.

[GotButterflies]

Zoomed heaters aren't that great at heating the air, imo. I like Ultratherms. Www.reptilebasics.com or www.beanfarm.com

Definitely need to carefully remove from the bottom of the tank- try not to move your tank too much- you can collapse any tunnels the crabs have made causing them to suffocate.

To insulate you can cover the rest of your tank (not the zoomed heater), with either Reflectix insulation, or use aluminum foil (shiny side facing the inside of the tank), then foam board or styrofoam.


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