Position of UTH

[ladybug15057]

Should the temperature probes be suspended in the air?

If you are using an UTH the substrate should have the probe in it on the side where the UTH is. And one can use a reptile thermometer on the wall in the middle of the tank for air temp.

[Andy]

I think I've given up on the UTH. I fail to see how it is going to heat the air in the tank to 28C when I have the thermostat set to 28C with the probe in the substrate above the UTH. I understand why the probe should be in the sand in that case i.e. the aim is not to cook the sand or the crabs, but I can't see how it is going to heat the air in a 40 gallon tank through the sand, especially in Winter. I was skeptical regarding the UTH when it was recommended in the reptile shop, because I'd done a lot of research online particularly in these forums, but as a newbie I was willing to listen to someone who at least owned reptiles.

I'm going to look for a ceramic heat lamp online, along with a dome reflector. If I'm going to use a heat lamp, I'm guessing the thermostat probe should be measuring air temp, rather than substrate?

There seems to be a large variety of ceramic heat lamps available. Are the generics as good as the branded ones i.e. Zoo Med, Reptile One, etc.?

[emmac350]

I'd recommend not scrapping the UTH completely...it may not heat your air completely but keeping the substrate warm might help your tank out somewhat.

I would recommend that your thermostat probe stay in your sand over the UTH even if you do use a CHE. Have the thermostat turn on both the UTH and CHE and have the bulb on the same side so the other side is cooler and you should be fine. Your humidity will tank when the CHE is on but it'll go back up when the bulb turns off.

[ladybug15057]

I agree with Emma. And the UTH alone to heat a substrate can take 3-4 days. I usually preheat part of the substrate that I put over the UTH.

[appps]

I measure the air just above the sand (just high enough to stop the crabs climbing up the cord) as I'm more interested in air temp than substrate as my heat comes from above.

What you will need to be careful of is putting it directly below the lamp if it's a small tank and the heater directly warming up the actual probe so giving you a false reading.

Oops nearly forgot. I've just bought my heat lamps off eBay over the years and they have been fine. Rather than a dome my hubby built me a custom bulb holder out of metal. It's important to only use the che with a ceramic lamp fitting too.

I have recently noticed a small ceramic bulb on eBay which I wondered might have been better for a smaller tank setup.

[Andy]

Thanks everyone for your replies, they are all much appreciated and you've all been very helpful.

I had the UTH on for about a week, but I found the temperature of the substrate tended to fluctuate quite a lot, depending on the temp outside the tank (it is Summer here, and Melbourne can have 4 seasons in a day). It is a 36" tank in length, and the UTH covers only a quarter of it. I think I will definitely setup a CHE, but I'll try using it in combination with the UTH. I'll need to keep the thermostat probe buried in the substrate close to the UTH so that the crabs don't get cooked if they decide to dig. But I'll monitor the air temp with the dual probe thermometer. If the air doesn't heat up enough, or gets too hot due to the CHE, I'll probably disconnect the UTH and use the probe on the thermostat to regulate the CHE. The thermostat will only be able to regulate either the air or the substrate, so I'll experiment to find out whether the combination heat source will work or whether I'll need to just stick to the CHE and regulate the output from that.

Annette, do you have just the one ceramic lamp in your tank, or multiples? Can anyone recommend the minimum wattage for a heat lamp for a 40 gallon tank (36" x 35" x 45")?

[appps]

I have a fairly typical 4 foot tank and one used to heat it fine. I now use two because I have day and night temps
I "think" they are 150w but I'd have to check.
Edited to add, the way my tank is set up my CHE are actually inside the tank though and not heating it from above the glass. Not sure how you were planning to hang yours.


I would note though that I would never ever use one without a thermostat. They pump out some serious heat. If I were you I would put rocks etc above the uth to discourage digging there and use your thermostat on the CHE instead. I wouldn't think you are going to need both though. You don't need to keep the sand warm.

[Andy]

Thanks for the pic and advice Annette. I messed up the dimensions when I typed them last night. It is a 3 foot tank, 14 inches wide and 17 high. I was thinking the 100w heat lamp should be enough, but I may need to do further research.

I currently have glass covering the top of the tank, but I will most likely get a part if it cut out so that the heat dome can sit in the tank, at least partially.I don't want the lamp heating the glass, but I think the glass will help in keeping humidity and heat in so I don't want to get rid of it altogether.

[appps]

Yeah, you couldn't do it without the glass, the CHE dries things out more so you will need it to keep humidity up.
I just took mine to a local shower screen company and got them to cut it. Just make sure you also ask them to smooth the edge so it's not going to cut you.

I just unscrewed my CHE that turns on at night and it's only 75w it turns out, so my other will be similar or 100w I would think (it's too hot to unscrew at the moment)
As your tank is smaller than mine your 100w should be fine.

[Andy]

Is there a specific reason for having a day and night lamp?

My tank is next to a floor to ceiling window. It is South facing, so doesn't get direct sunlight, but does get daylight and occasionally moonlight. I'm thinking that lights are not necessary for my tank, unless the crabs need UV rays for health reasons?