Ambient air temp too low?

Hey every one. I'm new o the forum and a new ball python owner. Just got him yesterday and I had a few questions. I currently have him in a tub, but his ambient temp is about 72 degrees. My house is usually in the low to mid 70s. His hot spot is reading 90. I was thinking I should move him into my 10 gallon terrarium since I have a day bulb I can put on the cold side to raise air temps a few degrees. He's a baby by the way. I would put plenty of hides and foliage as well. But I hear having too low of ambient air temps can lead to health problems and I definitely don't want that. I have a double mini deep dome with a 25 watt day bulb and a 25 watt infrared bulb. Should I switch him to the terrarium so I can bump up the temps? I don't plan on buying a heater or anything like that. And my dad like the house cold so I'm not changing the house temps.

I wouldn't move him to the tank, between the low house temp and the lights to raise the ambient in his tank he'll end up way too dry. Get a second under-tank heater with thermostat and set it at about 80*F for the other side of his tub, and put his cool side hide on it.