I have very shitty dial up so can't download your photos....they're too big or something.....but overfert is the very first thing that comes to mind. However....a ppm of 500 SHOULDN:T be too much for your plants.

Revised: The Complete Guide To Sick Plants,pH and Pest Troubles - PlanetGanja.com

I think probably part of your issue is the rockwool and it's associated overwatering and/or ph issues.

I've never heard of Superbrand Grow Aqua so can't help you with any advice on it.

Good luck.