Position of UTH

[Andy]

Hi all, I'm new to hermit crabs. Thank goodness for this website! I've been doing a lot of reading on it. I have two hermit crabs which have come from the pet store along with a starter kit, however, I'm in the process of setting up a 37 gallon glass aquarium for them (I want them to have plenty of space to explore and moult).

I will be using play sand (which is currently drying out in the sun) as the substrate, and plan on having a thin layer at the tank end with the UTH, and a nice deep layer for burrowing/moulting at the other end of the tank.

The tank is 36" is length and 14" wide. I purchased a ZooMed 16W UTH for it as that is what the person at the reptile store recommended, although I asked about ceramic heat emitters as well. The UTH is 12" in length and just under 8" wide. I plan on adhering it to the underside of the tank.

The UTH will fit nicely lengthways across the width of the tank, but will also fit running lengthways extending no more than 1/3 down the length of the tank. Either position I anticipate will create warmer and cooler ends of the tank.

Which is the most effective or practical position for the UTH? I still have concerns as to whether the UTH alone will heat the tank sufficiently.

[emmac350]

If you have doubts about the effectiveness of the UTH for your tank, look into a thermostat combined with the UTH and a ceramic heat emitter. I put the thermostat probe in the substrate by the UTH in my tank to make sure that it goes to the upper end of the warmth level I want. The cool side, thus, is below that and varies but never goes too low.

[Andy]

Thanks for the reply emmac350. I'm guessing that if I use both a UTH and a ceramic heat emitter I will need separate thermostats for each, as the ceramic heat emitter will be heating the air rather than the substrate.

I setup the tank today with the play sand and used large pieces of mangrove wood to create the deep and shallow levels in the substrate. I will probably just turn the UTH on when I've attached it to the underside of the tank and monitor the temp inside for a week. The weather is quite warm at the moment so what I'll be getting is the best case scenario. I may not find out if I need a secondary heat source until winter arrives.

[emmac350]

I have mine on the same thermostat. The problem is that it's almost impossible to use an air temperature-measuring thermostat for the CHE - as soon as the CHE kicks on it will turn off the thermostat. I have my CHE in a hood pointing sideways, not down directly at the tank. It heats much more indirectly (no beam of heat onto the substrate's surface) and even with both UTH/CHE on at the same time the air temp never goes above the low 80s, which is where the summer high in the tank usually is anyway.

[Andy]

That's good to know regarding the CHE and thermostat. Is the hood specifically designed for the CHE, or is it a hood that covers the entire tank?

Can you recommend any online shops with quality heating products?

[emmac350]

I'm using a Zoo Med Combination Reptile Strip. I've got a day UV bulb in the fluorescent socket with a moonlight bulb (low watt, more for trying to even out the night lighting than heat) and the CHE in the incandescent sockets. I haven't had any issues with it at all so far (except that one time the CHE was on and the hood got bumped and now I've got a melty bit the size of the CHE on the top of the back of my tank - but even that's nice because it's where I run my thermostat wire through!).

One note on the wire for your thermostat probe - cut a length of aquarium tubing as long as the part that's in your tank, open one end, and put the thermostat wire inside. Your crabs WILL climb the probe's wire to the lid. They will end up picking the outer covering off. And you will get to see the colors of the internal wiring's insulation. So wrap it in tubing, which will make it a little easier for the crabbies to climb but also will mean no exposed metal wires in the tank!

[ladybug15057]

Or one can use packaging tape to cover the wire mounted on the glass wall inside. It is slippy and hard for them to get a hold of.

[appps]

It must depend on tank size Emma. I have two che in my tank on thermostats which measure air temp and don't have any problems with it turning on and off all the time.

I was going to do a smaller tank conversion just for fun and was toying with using one of those mini che I've seen on eBay. Sounds like I might need to give that a bit more thought if it's going to have thermostat issues. Has anyone tried the smaller che in a smaller tank?

[Andy]

Well I stuck the UTH to the underside of the tank in the end. It covers about a quarter of the tank bottom. Over the area that the UTH is covering I have no more than about 2.5cm of sand, well below the maximum of 3.8 recommended by Zoo Med the manufacturer of my UTH, to prevent the trapping of heat and damage to the tank.

Over a week I observed the min and max temperatures at both ends of the tank using a dual probe thermometer. I had the UTH running off a thermostat set to 28C, and the probe buried in the sand on top of the UTH. The dual probes were poking into the top of the sand close to the edge of the glass. Unfortunately, the probe at the end with the UTH never reached anywhere near 28C.

Should the temperature probes be suspended in the air? I am beginning to think that my UTH won't heat the air in the tank sufficiently and that I'll have to buy a ceramic heat lamp and reflector dome setup.

[appps]

I've always measured air temp not substrate. I would make sure you have rocks or such over the sand where it is to stop them burying directly above it if you haven't already.

I was using a smaller tank for a while and found it took two uth to keep it warm enough but I had them attached to the sides with polystyrene behind them.