Hi!!! I have used autopots for years, and have never had a major humidity issue, or seen the top of my coco moist. Take what I say with a grain of salt as I am just a hot mess growing mom, but it sounds like maybe your valve is not closing properly?? Is your valve sitting properly and flat in the base? Is your plant showing any signs of overwatering? I always test my bases/valves before a new grow. I hook up an empty base with just a valve (no pot) to the res. I put about a gallon of water in the res and open it up. I make sure the base fills, then stops when its supposed to and doesnt overflow. Then I take water out slowly with a turkey baster and make sure the valve goes down. I also take out all the little little yellow rubber stopper thingies, roll them gently in my fingers, and put them back in.