Bottom leaves dying?

It's currently start of week two of flowering under a lifi plasma in hydro set up. However there is explosive new growth so I don't believe its nutrient lockout. I'll try and upload some pictures later so you can have a better idea of what I'm talking about! PH is around 6.5 and its in a Coco/moss mixture. This happened when I was growing under CFLs however not to this extent and I haven't seen growth like this either so I'm not sure if its the HID lighting or what.

So upon closer examination I realized there was white mold growing on the top of the substrate. Should I decrease the number of water cycles? Right now its running 5 minutes a day three times a day. The top looks fried on some plants because they got too close to the plasma.

not sure about this as i grow soil but i would suggest flushing getting ph back in order then addin nutes in moderation

what should my ph be using a coco/peat mix?

Not enough nutes perhaps...