Yes its because of bad humidity. Keep in mind low humidity can cause respiratory infections.
Cover up the top of them holes with some type of board or foil. This will keep ur humidity in the tank.
And why would you feed Friday and Saturday?
What would be the purpose of that? Feed him the amount of food he needs. Wait 5 days feed him again. You NEED to give him time to digests his food before you have him take more
Also them dial gages SUCK they can be WAY off