Copy-n-paste the troubleshooting form in my signature, then fill it out as best you can. Otherwise it can become a two week long game of twenty questions.

But I'm curious what you've been spraying on them if anything.
What is your ingoing ph?
How long have they been in the same pot?
What additives are you using? (anything with calcium or perhaps some extra magnesium?)
What kind of lighting? (why are you worried about light leaks?)