Rockwool 1st Time - WTF? Help!?

Hey all, this is my 1st time with rockwool and I'm a little confused why the plants are growing slowly and a couple look terrible. I'm just coming off a very successful DWC Bubbler Grow (see my signature) and have got a new Ebb & Flood setup with 5 different strains. Here are some facts about the setup along with some pics. I'd appreciate any advice you can share about experiences with rockwool as it's the only thing really different about my setup vs. the DWC grow.

Plants are about 2 weeks old
3X3X7 Home Box Grow Room
Ebb & Flood - 25 Gallon Res
6x6x6 Rockwool (Ph 5.8 soaked for 3 days prior to planting)
Flood 4 times per day for 5 mins each (3 day/1 night)
430 Watt Hortilux HPS on 18/6 Lighting Schedule
Daytime Temp: 76 - 79 F / Night Temp: 66 - 69 F
In Line Fan - 460 CFM
Ph: 5.8 - 5.9
PPMs - 300
R/O Water
Botanicare Nutrients with 1/2 strength recommended for seedlings (Pro Grow/CalMag/Liquid Karma/Hydroguard)

I started the plants with R/O water and a very low addition of Liquid Karma (much less than recommended). Over the last 10 days, I have very gently added the rest of the nutes and am only at about half strength of what Botanicare recommends for seedlings. This is the same that I used for my DWC and the plants were 10x bigger at this age and were generally healthy.

Help!?

I hate rockwool, Coco pellets give me more success.

They look ok, slow growth could be over watering, rockwool holds alot of water, if it doesnt dry a little the roots dont expand to search for water, only water it when its damp until the roots penetrate the rockwool.

and take the plastic off.

Mig, why do you hate rockwool? It seems to be the favorite of so many growers. Also, won't I run into algae problems if I don't keep the rockwool protected from the light? Finally, I have read many recommendations that say short, frequent flood cycles force old air out and new air in and is better than less frequent cycles. I appreciate your input and feel like a newb all over again.

Shit, maybe I'll just turn this setup into a hydroton drip system.

I just dont like it, its itchy, too much messing, it splits and dries quickly and molds easier in the climate here and coco pellets can be flushed and readied in an hour.