Sauna heaters with rocks are usually meant to have water applied for refreshing steam. Moderation is the key. Remember 1 ladle full of water every few minutes will fill the sauna room with steam, so please do not dump a whole bucket on the rocks. This will only cool off the rocks to the point where most of the water will just go through the heater onto the floor without producing any more steam! Be sure only tap water is used on sauna rocks as treated water from a pool is not healthy to breathe and it has chemicals that will corrode heater body.