Need help with humidity

In the tubs my snakes are in the humidity will not get above 30% if i spray it goes up to about 45% and then within five minutes its back down. The tubs are heated with belly heat and are set at 89 degrees on the warm side and the cool side is about 81 degrees. I tried making a humidifier like in the DIY forum but it does not seem to work at all.:rage:

What are you using for belly heat and substrate?

im using uth and just newspaper as substrate

Do you have too many "breathing" holes?

Well, this is unusual for a tub situation :weirdface
I also wonder about the number of holes you might have in the tub....
Have you tried adding moss to the tub?
Does the tub have a solid lid? (Probably, but...)
Is there room in the tub for a larger drinking bowl placed closer to the UTH?

Just noticing that your temps are the very lowest that you ever want them to go; so watch for that....

What are the ambients and what are you using to measure the humidity and temps???