Can't get enclosure warm enough

So, I've looked through every similar post, and can't seem to find good answers.

I have a baby who is still in quarantine. Meanwhile, I'm trying to get the levels in his permanent enclosure right. No matter what I do, I cannot get it warm enough. I'm still reading 79 on the warm side and 71 on the cool side. I feel like I've done everything possible to correct this, but nothing's working.

I'm working with a 35 gal tank. Its been covered on 3 sides and top with reflectix and foil tape, with only the lamp area left uncovered. I have a large UTH, hooked up to a thermostat, set at 95. I have a 100w ceramic bulb, connected to a separate thermostat (probe directly under bulb, on top of substrate), set at 89. I have a thermometer with a probe placed close to the back of the warm side, 2 inches above substrate, reading at 79. Another on the cool side, reading at 71. It's only gone up a couple of degrees the entire time I've been playing with it. What gives?

The only things I can think of are:
-Maybe the substrate is too thick
-Maybe the water dish (placed mostly under the lamp for humidity) is absorbing the heat
-Maybe I should put reflectix on the bottom, too? This tank has feet so there's a little airflow underfiberneath
-Maybe I need a second lamp, though I've rarely seen anyone do this

Pictures below. The light you're seeing is just florescent, for daylight. I have 3 hides, one over the UTH. The substrate I'm using is a mix of loose coconut fiber and cypress.

Help?

https://app.photobucket.com/u/Akphai...0-c0c77a98cefb

https://app.photobucket.com/u/Akphai...e-6864553e8ed9

I might've missed this, but where's your thermostat probe?

I'm having the same problem but I can't seem to get mine above 83 in my 40 gallon breeder.

It could be because of incorrect thermostat probe readings causing the thermostat to warm up to a different temp. BTW, the thermostat probe should be UNDER the enclosure, sandwiched between the heat mat and glass, however this isn't the only possibility to why the enclosure isn't getting hot enough.

A couple things......If you don't, you should have the UTH on the outside bottom of the tank and the thermostat probe should be between the UTH and the glass bottom. Then the best thing to do is to use a infrared thermometer gun and check the temp inside on the glass floor surface.
The UTH should have no problem getting the floor temp of the glass to 88-90. In my tank I have 2 UTH one keeps the floor at 89-90 with a hide over it and another on the opposite end keeps the floor temp at 80. I have a very small CHE which keeps the ambient temp at around 80. A UTH will do little to nothing for your ambient temps. Lastly what is the temp in the room that the tank is in? In. The summer I don't need the CHE but in the winter the room stays at 70 degrees so I bring it up a little. You might also want to find a way to check the thermometer you have is accurate as well as the thermostat. I have 2 identical thermostats one is off about 4-5 degrees the other is perfect. A 15.00 infrared thermometer gun can help you a bunch

What are your ambient room temperatures?

As vivi said, make sure the thermostat probe for the UTH is sandwiches between the heat mat and the bottom of the tank on the outside of your enclosure.

For the CHE, hopefully someone who uses those will chime in with probe placement suggestions.

Part of the issue may be that it sounds like you are actually measuring ambient air temps as opposed to surface temps. To measure surface temps you'll want to purchase a temp gun. You can get them for about $15 on Amazon and can probably find one at home improvement stores.

What kind of thermometer are you using to measure your air temps? Is it digital or the stick on kind you find at pet stores? The stick on kind are wildly inaccurate. You want a digital thermometer to measure air temps. A popular one are the Acurite kind, about $8-$10 at most Walmarts.