This viv just won't heat up!

Hi all! I am prepping for my first corn (and reptile!) ever in a few weeks. Trying to get the viv set up to perfection in the meantime

However im having some issues. I purchased a used 20Gal long with a 10-20Gal heat pad still attached. The lady before used it for her corn 5 years.

FOR SCIENCE I tested it with no thermostat to see how hot the bottom glass would get (no substrate either) and it went to anywhere between 87 - 100F over the course of 2 days.

Should be good then with a thermo I think as I move the tank to its new location and add 1cm or less of eco-earth and plug everything in.

I do know that aspen is superior but I inherited a TON of snake stuff from a friend and have about 8 bricks of the eco earth. So I would really like to give it a shot, plus it looks so natural
I was going to scatter some loose coco-chips over the top but I wanted to let the eco earth dry out some more first & I left it for 12 hours with the heat pad going to help it along.

Temps in the cage haven't gone over 73F on the HOT side in over 6 hours. The cold ringing in at a chilly 67F. This is baffling me! I know the UTH has the capability to put out the heat but for some reason it isn't? 2 different probes are reading it.

Not sure if im doing something wrong or if that part of the house is just so much colder?? I would really prefer not to use one of the overhead lights for many reasons.

I have at my disposal: 3 digital temp readers, 1 infrared light, 1 ceramic heat lamp, 1 reptile halogen light & 1 bigger UTH (huge though, made for 50gal + terrariums), 1 thermostat & 1 dimmer.

Sorry if this is really rambly and long <3 Would appreciate any advice.

Where do you have the probe for your thermometer (not the tstat) set?

the hot side probe (attached to the thermo) is nudged into the eco earth touching the glass over the heat pad. The cold side just sitting on the substrate.

Hmmm I don't know what to tell you then! Is the thermostat working right?

Aside from having a digital thermometer alongside it (which read the same the last time I checked) im not sure how to tell if the thermostat isn't working D: its set to cap off at 86'F but the temps haven't even risen that high.

The ambient temp of the house around the cage is only a few degrees different from the cold side too :/ im just baffled!

I would remove the thermostat and plug the UTH directly into an outlet again to see if the temps rise to verify the UTH is in fact getting hot enough. Don't change anything else.
The cause for the low reading could be due to the eco earth is absorbing the heat due to the high water content within it. I'm assuming you expanded the bricks with water per instructions. The probes inside eco-earth will get lower readings than inside aspen. A UTH will heat up the trapped air inside aspen more efficiently than the more compact eco-earth that was expanded with water. It takes 4 times the energy to heat water than it does air. It might take days for the eco-earth to dry out enough for the temps to rise. That's the case with Vivs that I use eco-earth in. Once the eco-earth dry's out enough and the readings rise then plug the UTH back into the thermostat and see if it works properly.
I don't use or like eco-earth for snakes though.

Thanks for the info that does make sense! I will try that and report back in a few days.

If its this much of a pain in the butt though I might just sell off the rest of this coconut stuff and go in for aspen. I'd gift it like my friend did to me but I dunno any people with amphibians around here D:

I am glad to see you are doing all of this BEFORE getting the snake! Many people put the snake before the UTH.

Daddio's suggestion is great, I am interested in the results.

Oh thats just me, I super prep and obsess over every tiny detail of a thing when im excited about it xD

Overnight I plugged the UTH with no thermo back in (I might have made sure the temp probe could touch the UTH glass but still had eco earth around it)

This morning the temps read:

Hot side: 89'F
Cold side: 69'F
House: 68'F

Iv heard about people baking their substrate to sterilize it, do you think baking the eco earth might help re. wetness? Or maybe bake some of the expanding coco-husk I have and replace the earth completely?