I would ditch the humidifier, that is probably what caused the mold. Hot humid climates are perfect for fungus. You want a lot of passive airflow, a good test is try lighting a lighter and moving it around the tent, if it stays lit especially near the plant then there is not enough airflow. At minimum the flame should be dancing around every few seconds or so. You don't want to directly blast plants with wind cause then your leaves will get wind burn, but wind burn is honestly better than mold.
Judging by the mushroom growing from your medium there is probably a lot of mold spores in either the room or soil.
When you say it was getting hot, how hot? Do you have a hydrometer to tell you temperature & humidity?
To avoid mushrooms and mold you can use something like Dr. Bronners Castile soap @ 1ml/gal in your feed water, it will suppress mold spores and also kill larvae if any are present via suffocation. And you should only have to treat the soil a couple times before any viable spores are dead.