I have a similar question on rockwool. I'm using a top drip. I have a 8 gallon res with a ~200 gph pump and maybe a 2 ft. head. It doesn't drip, the water streams out which I'm not crazy about. Seeds were started in a peat product and transferred to the hole in the center of 4x4 rw cubes. I was planning on watering 2-3 times per day for 15 min but the rw is holding so much water that I'm worried that feeding 1 time per day would be too much. It's been about 24 hours and my cubes are still heavy. I have normal to below normal humidity so I'm not sure why they're holding so much water for so long. It could be the airflow but i don't think so. I plan on moving to hydroton but I wanted to veg for awhile in rw alone. Is this normal? Should I cut back on feeding to let the rw dry a little bit? I don't want the root rot! Thanks in advance.