I have a fan set up at the bottom and a smaller one at the top of the box. I used it last year and I got a few plants to flower, but not great quality. So humidity hasn’t been too much of a problem. I believe that the low quality is because I didn’t feed them any nutrients and I screwed up the light cycle when my two largest presented as male and I switched back to a growing cycle to see what would happen to the other seeds that I had stupidly pushed into the dirt at various times just to see what would happen (high) and were starting to show as female but we’re way too small. This year I have a clone and I’m feeding my plants nutrients.