Okay. So I'm guessing I should not have given any nutes what so ever.. I gave 1/4 strength and growing in rock wool and going to be doing DWC these are 7 days old and are curling and tips and middle have gone brown... could not help my self should of waited till I got an ec and ph pen !! Looks like I'll be starting again.
It's been years since I used rockwool and DWC, but I always started with 1/4 strength nutes pH'd to 5.8 - 6.0 - never just plain water. I can't see your problem clearly because of the blurple lights but my guess is that your pH is messed up, not over feeding. Did you pre soak your rockwool before you used it? An ec pen isn't necessary , but a way of checking your pH is a must, whether you use a pH pen or the drops like I use, you never give your plant anything without pH-ing it first.