Hi thanks for the reply, my bombshelter/storeroom is quite air tight (except for ventilation hole on top), seldom open up, and dark inside, that is why it is a perfect place for mould to grow.
Based on your description, think the petite dehumidifier will work if i on 24 hours a day. I am ok to clear the water once every 2 days, if I can keep the mould out from the storeroom.
Where did you buy yours, what brand and how muchie?