Have you tried monitoring what is running for a couple cycles, taking notes hourly on temps, humidity, and what is running at that time, including items on thermostats and your humidifier?

Looks like you will need to improve your passive intake as well. Try moving items that may be blocking air flow.
stinkyattic Reviewed by stinkyattic on . Why do temps go up at night? I've searched and didn't find an answer. I have a Homebox S (31.5" x 31.5" x 63" - 6.89 sq. ft.). We have central A/C set on 76 F 24/7. I'm running 16 26 watt CFL's and 4 14 watters. The ocsillating fan runs in the box 24/7 as do the lights. The exhaust is handled by a 500CFM fan pulling through a DIY carbon filter. Our plants are still vegging so everything is on 24/0. During the day, the ambient temp inside the box runs from 81 to 84 degrees. At night, the inside temp will get up Rating: 5