What he said. Rockwool will stay much too wet if it sits in water. Your plants will rot. Some roots in water all the time can be good however, especially if you have power outages. Expiriment with on/off flooding times. You goal is to have the roots as dry as possible without stressing the plants.

Clay pellets in my opinion are much better than rockwool. Not so many moisture-related problems, and completely reusable.
Opie Yutts Reviewed by Opie Yutts on . First Timer Need Some Help Me and a buddy just made a home made flood and drain setup and its done we just think we ran into some problems. for one the trays we got when they drain they do not drain all the water out it leaves some water at the bottom maybe a half a quart?.is that gonna drown the plants or will that be ok? and the other thing is the pumps we bought to pump the water to the trays we think might be to powerfull. they fully fill the trays in 5 minutes and draining takes around 10.We will be using Rating: 5