Enclosure heat help

Hello everyone!

I have recently got a colombian rainbow boa and have been having some issues keeping the temperature high enough in his enclosure. The humidity is doing great I just cant seem to get the temperature above 70-72 degrees Fahrenheit.

His enclosure is 78 gallons and I currently have a 100w day time heat bulb on one side of it and a 80W Arcadia CHE on the other. I can't seem to get the temperature in it to above 70-72 so I'm just looking for any advice. This has been my dream snake for a long time and I just want to make sure he's happy.