I have a friend growing in a tent, hes grown before inside and out and never had any issues, now his plants are doing poorly, tgrowth sometimes seems to stop or at least slow dramatically. They're not near as tall as the should be but are pretty bushy, tent has adequate ventilation and fan is more than enough for tent size, every time he waters (when pots are almost bone dry) the plants wilt within an hour or so, he put some plants outside during the night (after watering and they wilted) and by morning (before sunrise) the plants are perked up and looking nice, he feels like something is wrong with the air (quality) in tent. Any ideas? Tia