You never heard to pre soak your rockwool in 5.5 PH water???? Seriously?
Thats one of the first thing you should do with your rock wool is soak it in PH 5.5 water ( some say 1 hour some say 24 hours) then you take it and shake it like some dice to remove the water. I hate rockwool you can easily over water your seedling. I ditched rockwool and now only use rapid rooter plugs.
I have really good luck with the plugs...I tryed rockwool with seeds but then I put them in dirt and then took cuttings,,then put them in the plugs and let them root...
I really didn't like the rockwool going into my hydroton...I just haven't done it....I see people here that do... I just didn't like it...
My experience with the plugs has only been good...when I transfer from my clone bucket to my five gallon...They never stop growing there has been no shock from stransfering them...the roots are nice and long and I just rap them around the bottom of the baskets and they take off....
heres some pics
The pic with the long roots took 22 days in the clone bucket
the pic with the basket was after 3days in the big system
The other pic is my clone bucket set up...and I have gotten away with growing clones for eight weeks in these's buckets...they get pretty big and crowded after eight weeks...the trick was to not mess with them let the roots just ball up in the bucket...then when I pulled them out of the bucket I had to cut the roots with a pair of sizzors...but they were still pretty long...and they still took right off