This could be a big debate. I use little one inch cubes for clones or seeds seems to work best for me. However under different circumstances rockwool can hold way to much in the wrong place. The root ball wants to stay moist with lots of air , long water roots can stay submerged and still get h20 from the water. You don't want rockwool too wet. atvs22 your sytem is tuned in and is working very well for you, I could take the same system and Kill half the plant life on earth with it. LOL It's really learning to tune in your system.