If that was my enclosure, I would make a wooden top for the left side. Cut a small hole for the fogger as far to the right as possible in the wood. Then cut a larger hole as far to left as possible, sit over that hole a dome shade with a 100watt CHE in it. CHE needs to be on a thermostat. Set so the coolest end is at 82f. Then have a fluorescent uvb tube hanging from the wooden lid at about 8" above tort level. Make tube aboutvhalf the length of enclosure, so its darker in the cooler end. Light gradient follows heat gradient just like the sun.The bulb on the right says sun glo 40w(blue/purple one) and the left says sun glo 150w.
The lids are just aquarium lids. I was planning on building a wooden top for the tank like I have with my snake. Originally I was trying to find a cage for the top and put a small light on either side and use the double light for my snake terrarium but I have limited access to cage lids where I live on an island.
I raised the light up 12" off the ground and it has jacked my temp up to 90 Fahrenheit
Use the sliding door on the right to open for feeding etc. Keep that closed otherwise. Your substrate wants to be about 2" deep with coco coir, cover half the coir with a layer of orchid bark so your tort has a drier area to retreat to. Have some spagnhum on the coir side too.
Hide at each end.
Try and get temps 82f ish. Mine is 88f down to 82f. No basking spot. Turn tube light off at night. They need it dark to sleep.
Your substrate wants to be moiste and warm. Not soaking wet through.
Sounds like your friend was using the purple light at night, don't know what he was using for heat at night.