Sick seedlings, any help is appreciated :(

http://i142.photobucket.com/albums/r...0-21231211.jpg

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I'm new to growing, and I was hoping someone with experience could help me diagnose what's going on with these. These are technically a friend of mine's, but I've helped him care for them from seed. They're all Jack Herer seedlings that were germed in rockwool, then put into a soil mix in a plastic cup. Initially he didn't put holes in the bottom of the cup for drainage, but they were added weeks later. As it is, these seedlings are about 3-4 weeks old, and within the past two weeks they've been very stunted in growth, and the leaves started discoloring by turning yellow. Now they've developed a brown and even redish hue. The leaves are dry and crumbly. They are watered when the top of the soil becomes dry. The seedlings in the photos are goners I'm quite sure. But not all of them are quite as severe.
They have never been fed nutes, and were germed inside under a weak single strip flouro. Their growth was great and promising, but the air circulation in their little room was practically non-existent. So we moved them under the 4' 4 bulb T5 Flouro in a different room with good air circulation to veg more. But here's the catch, the T5 only had red-spectrum bloom bulbs in it, and only after we moved the seedlings under this new light did we start to see them stunt and wither. We have since gotten some proper veg bulbs. They're much more blue.

Unfortunately my friend doesn't see much use in investing in a PH meter, so I can't tell you the PH, but I think I'm just going to do the right thing and pick one up for him.
We've mulled through a lot of theories, but I'd like someone with experience on the subject to take a look. Could it be disease or fungus? Could it have been the bloom spectrum bulbs? Could it have been from the initial lack of drainage in the cups? Or do they just need nutrients? Or, have we overlooked something completely?

Any help is appreciated. We want to prevent this sort of thing from happening whenever we can.

I had a similar problem recently but mine was a lot less severe. While researching I come to the conclusion that my issue was a CalMag deficiency. They got stunted and wouldnt grow anymore. Once I gave it 1 tsp of CalMag per 1 gallon of distilled water they have started growing again and they look much healthier. But over watering can cause some serious issues too. That would be my first thought since u had no drainage holes for some time. Wait until the soil dries out then try to treat it for CalMag. You dont have to take my word tho I am also a new grower on my first time. I have researched a lot tho.

I'm glad to hear you found a solution to it. I'm going to give that a shot and see if I can't save some of the seedlings. Thanks for the info :) And we're picking up a PH tester, so we'll be able to tell if the plants can even use the nutrients we give them.