UTH placement!!

[ciaraalston]

I've read several posts about where to put the UTH. Ultimately, you should NEVER put it under the tank. Everyone goes for the sides or back. But here's my dilemma.....
I put the heat tape (Same as a UTH just not insulated) above the substrate. It was about halfway between the top of the substrate and the top of the tank. temp couldn't hold. It would fluctuate between 72 and 78... (I also have my heater from the 20 on the side of the tank, it sits above the substrate. And i have the very small hermit crab branded zoo med heater in the back right where their mason jar sits because they like warmth in there)
so we moved the heat tape lower, so that the top of the heat tape was aligned with the top of the substrate. The temp slowly climbed and has maintained between 80 to 82.9 (I have the thermostat set to 83)

So here's the question....
I thought I read that it's recommended to put the UTH above the substrate so as not to dry it out.... is that an absolute steady "suggestion" or just a case by case senario..

In case y'all need details of the tank to give accurate readings, I have bubblers in both pools, my humidity reads 85% on average, and the substrate is 6 bricks of eco earth and 1 bag of play sand.

In my 20, I had the UTH sitting half and half... the middle of the UTH landed right at the top of the substrate. I never had issues with dry substrate (that I know of) but I also have never had 10 inches of it before.... Will my bottom be dried out???
If so, what can I do?

[[If none of these descriptions make sense, please let me know and I'll add pictures for visual reference. I'm terrible with describing. Haha]]

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[wodesorel]

I have always used a pad that covered the entire back of my tank from top to bottom, including all the substrate. It is the only way I can get enough juice to warm the whole thing in winter. It also gives the crabs different temperature options when it comes to molting, as the vast majority of unheated substrate will end up being room temperature.

Honestly, I don't know where or when people started recommending using pads only above the substrate. That may work for warm climates or warm houses, but it'll end up being undersized for most northern homes! Prior to a couple of years ago the HCA recommendations were a pad that covered everything, so people wouldn't be stuck having spent money and still end up with too cold a tank.

[ciaraalston]

I live in the south, ultimately the average temp is HOT!
But I keep my house around 72/73 degrees. And I've noticed with the crabs, that they're much less active at those temps. Mine love hot days, and when the tank reads 90F, I'll find a crab hugged up against the heater. It freaks me out and I worry they're going to burn, but they love warm temps. That's why I added the tiny one right against where their mason jar hide is. The jar is buried and the heater keeps it nice and warm. But I don't need a thermostat because it's such a small heater (smaller than my hand and doesn't get very hot at all) so I don't worry about overheating them.
I just wanted to make sure because like I said, I've never had this big of a tank. My substrate before was barely 6 inches deep.... I'm working with about 10 inches of substrate now. So i wanted to make sure that I didn't dry out the bottom because my tiniest buried immediately after placing him in. Humidity reads high all the time with the bubblers, but I wasn't sure if that would keep the deep substrate moist or just the top...

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[Motörcrab]

I believe the placement of the heater is personal choice as long as it isn't underneath the tank. Like Wodesorel stated if the entire back is covered it will heat up the substrate next to the glass eventually drying it out.

You will also get different temperatures readings depending on where you have your heat probe in the tank. If thermometer is on the opposite wall of the heater it should read a little cooler than if it was on right next to the heater.

Right now in our 75 I have the tank temperature set to 86 on my regulator. The probe for that regulator is about 5" above the substrate about half way between the front and rear wall on the left side glass (9" from the heater) that is giving me a reading of 85.6. We have a digital combo reader on the same side wall but near the front glass in the corner about the same height. That one is reading 81. We have a third one, that I need to move, it's on the back next to the Ultratherm. 3-4" off the substrate that is reading 92. The crabs can move around in the tank to where they are most comfortable. I believe if they are too hot they will did down into the substrate to where it would be closer to room temperature, or go swimming in a pool!

Hopefully that helps. You may need to play around with the location of you thermometer, maybe add a second to see how the temperature can vary in the tank.

[ciaraalston]

What do y'all recommend for when the substrate dries out? Should i take the tank apart and mix it all up, or just mist the top along the back wall?

[JoeHermits]

You should be able to mist it along the back wall.


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[Motörcrab]

As a precaution it is a good idea to unplug your heaters for 10-15 minutes and allow the glass to cool down before misting near them. They generally don't get hot enough to crack glass but better safe than sorry. I would mist the substrate heavily near the rear of the tank, but not enough to cause flooding. Also be sure to check if anyone is down before misting away. If someone was down I would only lightly mist to wet the top layer of substrate.

[wodesorel]

I gently pour a few cups of warm water along the back myself.

[aussieJJDude]

Sand tends to wick out moisture from wetter areas anyway, which will help ensure that the substrate isnt ever at a stage of being saturated.

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[ciaraalston]

i totally forgot to reply to this thread but thank yall so much for the advice!