I cant keep a proper ambient temp in my 40 gallon breeder tank for my ball python. Yes, I know that the source of my problem is having too big of a glass tank, but I won't change my BP to a new enclosure.

Humidity does perfectly well with the screen top completely uncovered. I also keep some moss in there for shedding or if the humidity gets too low. But I can't keep a proper ambient temp.

I have a properly sized uth regulated by a thermostat for the hot side, and the hot hide gets to the proper temperature. I also have a smaller uth meant for a 20 gallon taped to the side of the cage next to the cold hide constantly on, but that doesnt really do anything for the temperature besides creating a hot spot on the glass.

My house is usually around 71° and gets as low as 65°. What I started doing is turning on my 100 watt red incandescent light bulb and leaving it in the middle of the cage on overnight. The highest it ever got at night was 75°. I overslept and woke up at around 3:30 PM and it was at 77° wich was the highest temp reading recorded on the thermometer.

My humidity didn't suffer too bad since I soaked the moss before I went to bed. But thing is that I can't leave this lamp on 24/7. It will dry out the air way too much and I would have to constantly spray down the moss. I also think that the red light bothers my snake, I pulled an all-nighter and checked for my snake, he never left his hide or even poked his head out. I'm not sure what it meant but he could've just not wanted to leave the hide.

Another problem is that me and my family leave the house every other weekend to spend 2-3 days in my grandparents hoise across the city. This is usually long enough for the house temp to get as low as 55° in the winter.

I'm torn on what to do. I have the 20 gallon uth and the 100 watt red incandescent light bulb on a 5.5 inch dome light fixture to work with. I dont plan on doing anything crazy with the cage or switching enclosure, but I can invest in a CHE and/or thermostat. Pretty much anything that doesn't break the bank too badly.

P.S. Does the temperature inside the cold hide need to be different if the ambient temperature is perfect?