I run the water level far enough under the bottoms of the plugs, that they stay damp, but not soaking wet (can't give a distance, as that depends on the air pump and stones) ... the photo shows them too wet, really, I dropped the level down after ... that's the beauty of the RapidRooters, supposedly, the way they retain and drain water, is just right for seeds and clones ... you need to watch the roots don't dry out, that's about it ...