The best remedy for and fungus,mildew or mold is ventilation,ventilation and more ventilation... Humidity should be at a low but not low enough to take away from the plant's... They need a lil' humidity.... Even with a hydro system... Where water and moister are present all the time then ventilation is key to no condensation that can raise humidity and there come's the mold,fungus and mildew... Just a preventive note..