Quote Originally Posted by Help_Needed
Let me repeat myself....the cube is NOT SUPPOSED TO DRY OUT!!! It doesn't need to - not in a DWC, anyway. Air is circulated through the reservoir with one or more air stones, disolving oxygen into the nutrient solution. The plants get all the oxygen then need from the solution.

And being wet isn't what causes root rot in a DWC system either. Usually root rot in a DWC is caused by res temps that are too warm; insufficient air flow into the res; or roots that grow too thick and restrict water circulation. Failure to completely clean your system between grows can also cause root rot as well as other diseases. But not letting your rockwool dry won't do it.
Well, maybe I used the wrong term, 'dry out'. I didn't mean to turn it completely dry. If a plant is in a 5" cube with very little or no roots coming out yet and is constantly sitting in a bucket or a tray with the bottom inch of the cube emersed it cannot thrive whether there are clay pellets around it or not. The constant water will prevent oxygen from reaching the plant.