just keep a 1/4" of water in the bottom of tray...no need to replace jiffy peelets anywhere. I ahve grown seedling 6-8" high using just a tray or ebb and flow. when you get 4-5 alternating nodes...then you put them into system on 400ppm of nutes. Not before. All they need now is water.

Pete. rockwool only has problem if you leave it sitting in water...It wasn't designed for that. It was meant for drip or ebb and flow...where water is cutoff for extended periods of time.