Flouro lights are stronger than you think sometimes. I'd say 99% of the time if all your seedlings turn red/pink it's because of light burn. Unless you miraculously got a full batch of variegates.
If it was too little light they'd either be green and stretched out, or white and stretched out. And cutting back on watering when they're turning red is a bad idea. They're getting burnt and less water will just make it worse.
I might also add that if the humidity/moisture level is low they will burn a lot easier. Are they covered?
Interesting! It may be that I weened them off of humidity too fast, increasing their sun burn. I had them in a humid box, and over a couple of weeks cracked the lid more and more, and pulled them out a few days ago. Right now they are in a well-lit but not much direct sunlight part of my house. I'll put something up to keep all of the direct sunlight off of them, even though it only amounts to about an hour per day of direct. They were also red before I moved them. I'll give them some water. How often is it good to water them at this age?
They are all in a large, shallow clay pot. On one half of the pot are seedlings that I GA3'd and on the other half are au naturale. The GA3 ones are less red, paler, taller, and skinnier, whereas the natural ones are shorter, fatter, and most are read with some very red. It's interesting that the GA3 ones are so different than the natural ones.