HCA: Hermit Crab Association

I'm trying to figure out what watt of heating bulbs to get for my crabbies. Currently, the room around the tank is around 65 - 70 degrees and the tank itself is sitting at a solid 70 degrees (which is why i'm desperate to figure out these things!). I plan on having the heat lamp about 4 inches away from the glass. I'm also getting a heat lamp that has a dimmer if that helps anything.

Should I get 75 watts, 100 watts, 150 watts or what!?

What type of heat lamp are you going to use? Day/night bulbs, incandescents, or a ceramic heat emitter? How large is the tank? I don't own hermit crabs, but the only advice I can give is to get a high wattage ceramic heat emitter and couple that with a thermostat. You can always reuse a higher watt heat source if you decide to upgrade your enclosure to something larger, but the thermostat can keep the heat in check for the current enclosure.

And I always like reminding people that when experimenting with temps and humidity, to run the enclosure for a few days until stable before introducing crazy critters

I would still recommend an Ultratherm that covers the entire back of the tank. Same cost, and no needing to replace bulbs.

Otherwise, the questions that nepenthes asked are needed!

I second Wode. I've had the same Ultratherm for well over a year, insulated it, and have steady mid 80 temps. I do not use lights at all with my tanks.

I'll second wodesorel and soilentgringa's comments: an Ultratherm has been on my 29g for a year and maintains mid-80s temps along the back and mid-high 70s in the cool front corner -- I haven't even needed to insulate my Ultratherm as I'm in Arizona with fairly warm to horribly hot ambient temps all year. The only light I use is an aquarium strip atop the hinged glass hood and that is just to give the crabs more of a day/night cycle and to enhance viewing.

We have a 15 gal with 3 small hermits (now 2 due to a sad molting attack incident) and use a small UTH and a mini UTH. We couldn't get the heat up past 72 so got a light fixture on top that holds a day bulb and night bulb. Problems continue and it's a constant stress. Main problem with the bulbs is they zap the humidity super fast. We find a balance during the day with the day bulb and a wet wash cloth (safe water of course) but only 4x per week when one of us is home to monitor. The high watt red bulb was too dangerous to the unmonitored humidity during the night so we got a 15 watt bulb. Lifts the heat about a degree. :-/

Reading this site I'm concluding that we must get more UTHs so that's what we're going to do and stick them on the back. I'm not very experienced but I find the bulbs to be high maintenance for reasons above. I wouldn't recommend.