Struggling with Seedlings

[DailyGardnr]

Area: Indoor
Medium: Rockwool
Grow: DWC
Age: 13 days from germination
Light: 24h (moving to 20/4 today) 3 x 13w CFL, 3x15w LED, 12" away from seedlings
Temps: 21C to 24C
Strains: WeddingCake, PurpleHaze and WhiteWidow

Issue: The seedlings are turning brown... What am I doing wrong????

Aug2 - Seeds germinated (in rockwool) with seedling mat
Aug7- Sprouted plants moved under single CFL (unsure of wattage... don't use this light anymore)
Aug9 - Moved to netpots w/ hydroton to shade rockwool and waiting for roots before transplanting to DWC
Aug13 - Noticed the issues seen in the attached pictures

Please help me! I am having issues getting strong, healthy seedlings. What can I do differently/better?

 

[chemistry]

Water/feed them at least 4 times per day over a 24 hour period. They look a bit dry, when they get that dry the new roots dry out, you need to avoid that at all costs.