Plants loosing vigor??

My first grow...I am growing hydropincs and just moved my plants to larger rockwool cubes. They were in small oasis cubes under constant watering tray under 24 hours of light using 80W flourescents. Roots grew out and plants were looking very healthy (about 8-10" tall). I just moved them to the larger rockwool cubes after 4 weeks and placed them under a 1000W flood and drain system. I have them under a 2-2-2 nutrient solution using the hydroponics 3-part system. I switched the lighting schedule to 18/6 and flood twice a day for 10 minutes. I've noticed two days into it that all the plants have begun to wilt, many yellowing at the bottom leaves, one plant appears to be drying out and leaves curling and twisting up. Very obvious changes. Also some brown patches have started to show on some. My pH is at 6.1 and the light is not close enough to burn them. I have adequate ventilation. I don't know what could be the problem??

Did I wait too long for the roots to grow before putting them in the larger rockwool cubes and so now they're not feeding right?
My resorvoir water does get cold?? Could that be it?
Should I flush it and go to a 3-2-1 like I was originally??
Input would be appreciated..tnks

It sounds like transplant shock. It's best to use a stress reducer such as Super-Thrive when transplanting and go easy with the lights until the plants have recovered.

ive been tryin to figure out the same thing in my nutes too cold post.. mine started doing it at about 3 weeks after vigorous growth now doin the same thing.. it was after i moved them from a 400 watt mh to a 1000 watt hps in the basement.. i tried everything and my environment and nutes are perfectg.. dont knwo what it is if you figure it out let me know

Well I got so worried that I ended up flushing my plants with luke warm water and replacing the nutrient solution to a 3-2-1. I also cut back a lot on the ventilation....I have a passive system which blows air out and brings air in from the attic. I think I was cooling them too much despite the 1000W being on in a small room. Room temperature increased and i noticed immediate results for the better......I'm also used a heating pad to help prevent the nutrient water from getting so cold....I'll keep you posted.