Heating problems with 28q tub

Hello All!
I am new to ball pythons and will be getting my very first one in just a few hours. I've read numerous posts and the care sheet here on the forum and have tried to do everything you guys all commonly recommend but I've run into an issue with heating my tub with my UTH.
I bought a 10-20 gallon UTH, which I think probably only covers 1/4 of the floor of the tub (I know 1/3 to a 1/2 is recommended), and I have it on a thermostat set to 94 degrees. Now the basking spot (below substrate) is a perfect 94, but the ambient temps in the tub are at 69-71 degrees, measured with my acurite with probe. oh and I'm using a thin layer of newspaper covered by a thin layer of eco-earth (to help with humidity) as substrate.
Is the ambient temp ok as long as the basking spot is good, or should I increase the size of my UTH?

Thanks so much for suggestions!

Is your tub pretty tall? Getting one that is only 6 inches or so high, might fix the problem. 69-71 is on the low side, especially for a tub. I try to keep mine around 80, but it dips to 75 during the cold months in my 41 qt tubs.

What is the basking spot above the substrate-where your snake lays.

As for the mat only covering 1/4 of the tub, that's probably the main problem. The more area the mat covers the better it will be at keeping the ambient temps up.

Thanks for the reply! the height is only about 6 inches, and the temp (using temp gun) was 71 above substrate after an hour of letting it run and heat up. I'm definitely just gonna get a bigger UTH while I'm at the pet store today. Really wish I would've thought to check it sooner so that I could get the UTH for half the price online. Hopefully this is my only snag. Thanks again!

It sounds like you ambient room temp is quite cool. Tubs do not hold heat well and tend to cool down faster than they heat up. If this is the case you will likely need to find a way to insulate the tub and or increase the ambient room temps. Ambient air temps are important to thermoregulation.
They Ideally are between 78-85ºF I would be seriously concerned if they were below 72º for any length of time.

Ambient air temps effect snakes core temps. They have a long lung and (not all) a short small lung that is an assist more than a functional lung. The long lung runs past the liver heart and every major artery and veins run along it. If the air temp is cool, the air in the lung is cool this will drop the blood temp and the core temp as well there is little chance that warming just the ventral muscles will alter the cool blood temps.

The room temp is about 70 degrees right now (our house is drafty so its cold in the winter but hot in the summer), so yeah it is pretty cold. Do you have suggestions on how to insulate the tub? And what kind of enclosures are suitable for snakes but at the same time hold heat better? I just went with the tub because so many people said they are easier to heat :confused:
thanks again for all the replies, I really appreciate any help I can get!

Tub heat up easily due to poor insulate value they do not hold heat well for the same reason. IMO they hold humidity well but are very hard to heat unless you have a 'snake' room that is around the 78-80 range.

There are enclosures that do better in cool rooms but are costly. Vision, boaphile, showcasecages, and a handful of others I'd avoid top opening as they have similar issues. It might be a good idea to wait set up a tub and when you snake gets closer to adulthood then start looking at better ones.

I am guessing you are not interested in heating a room? I get it I am also in a drafty place.

You might try using hard foam insulation tacked on the lid and some on the back. Remember you need ventilation too so keep some holes clear. The other thing that has worked for some is to build a small case around the tub figure bottom, sides and top enclosed some have had success with this type of set up with a fluorescent light in the back corner. They get warm but not hot so they make a great secondary heater to warm up air temps.

Thanks for the suggestions! I've been watching craigslist for used cages (I've seen a few boaphiles but they were too far of a drive) and I've been planning on building one for my beardie since heating her glass exo terra requires 150watts of lighting. Once I get the melamine cage built for the beardie I can bring the smake cage out to the living room where it is slightly warmer. Luckily I have plenty of foam board since we use it as insulation around the air conditioner, so I can put that around the tub. Luckily when my husband catches up to me and graduates college we can start having a new house built and I will have a room specifically designed for my reptiles.

luckily the guy thought I was coming tomorrow to get the snake and not today, so I've had all night to experiment with the tub and my spare 10 gallon that was sitting in the garage. I moved the tub to a different room, in a small square area under a desk but on top of a wine cooler, and covered the area in towels to help hold heat around the tub. Now the Acurite is saying ambient temp on hot side is 84 and on cool side 78, and my temp gun is saying floor temp is 93 (on top of newspaper) on the hot side and 80 on the cold side. my thermostat is set at 98 degrees and this is a temporary fix as I ordered a bigger UTH to cover half the tub today.
do these temps sound acceptable for a week or am I still way off.
Thanks so much for all the help everyone!

84 is a little cool 78 is ok the hard part is the ambient temps the uth will take care of the hot spot. Make sure you control the uth with a t-stat a rheostat need stable temps to work well.

im having the same issue, i have a probe on the floor of my sterilite bin, and the thermometer/hygrometer on the other side. and under the substrate is 95F, (not sure what it is on the surface... using a 1" thick bark substrate) and the thermometer is reading 72F on the other side, which is only 2 degrees warmer than room temp, with a humidity of 60%

my UTH covers about 1/3 of the bottom, and is hooked to a reostat. (currently at about medium/high) Its been sitting like that for almost 24 hours now..

so ill be experimenting with ways to keep heat in, and ill let you know if i find a way.