How to fix this temperature issue?

[akane]

I'm not entirely sure if you need to heat the cool side for a ball python or if a CHE and other bulbs are a good option but I do use CHE, sometimes infrared incandescents (dark night bulbs), and for daytime heat increases halogen bulbs so I have put them on a variety of sizes of enclosures. Including starting with all screen top aquariums and their problems. As I upgrade my growing snakes nothing is staying a screen top except the low humidity rosy boas that are ideal closer to 30% humidity so I haven't setup bigger than various 40gallon shapes.

Whether the heat lamp gets too hot depends how hot it's making the enclosure and how much the room temp could fluctuate. I wouldn't think you'd need 75w of supplemental heat on the cool side when starting in the 70s. A thermostat is never a bad idea anyway and necessary in most situations for safety. My oversized enclosures with species that are fine with a cool side at room temp and a very stable 68F room temp I can often just adjust wattage with not really any more risk of it truly overheating than a thermostat failing. When aiming for a more even temp across the enclosure, a species that doesn't handle as much of a gradient or is sensitive to small fluctuations, not enough space for a good gradient, or an unstable room temp you'd have much more risk of running into a problem.

I find brand of CHE makes a huge difference if you ever use them instead. I have some 25w bulbs that run hotter than 75w of another brand. The various incandescents don't seem to vary as much but I can generally use 50-75w by itself for a hot side of ~80F in up to 40gallon aquarium sizes. If for no other reason than the annoyance of trying to find the right bulb for the right temp I am pricing thermostats for any of my heat sources that don't already have them.

A screen top tank is likely to have humidity issues for a ball python and adding a top heat source will make it worse. I have been redoing all of mine with corrugated plastic (coroplast) or enamel waterproofed plywood lids. The coro can be easily cut to fit an existing aquarium lid frame with a gap for an external top heat reflector, light source, or just vents if you install everything inside the enclosure. My 2 sealed plywood lids so far have the CHE in complete wire guards in the enclosure screwed under a vent that also allows the cord out and also have vents on the cool side covered in screen door mesh. In larger enclosures an RHP is preferable and would reduce humidity loss some but I find few narrow enough for most aquarium sizes and considerably higher costly. Easier and cheaper to stick an agptek fog maker in a plastic container somewhere in the enclosure to humidify against a bulb heat source, which I've done with one tank, or DIY a stronger ultrasonic fogger. There are youtube vids of using agptek's fountain mister/fog makers that range around $7-$10 on somewhere like amazon.