Question
I have had gray mold appear on the soil in 4 inch pots of plants that I am growing in the house.  I have about 100 pots and it is on all of them.  I have a fan blowing on them 24/7 so it is not air curculation.  could it be I am watering them too much?  Thanks Jack

Answer
If this is new potting soil and the plants look OK, I would say what you are seeing is of no concern.  Many fungi will grow as saprophytes on fresh organic matter and pose no threat to the plant in the soil.  I would do nothing but wait and see if it goes away on its own.  If they can be put in sunlight outside, that may hasten their disappearance.  I dont think you have anything to worry about unless you are allergic to fungal spores.  Good Luck.