This is a before photo of my orange, red & yellow bells

It looks like bacterial spot to me. The link below goes to a blog post about the problem. Initially, I thought it might be powdery mildew, because I can see some - it's the white stuff on your hydroton pebbles. I would try spraying everything with hydrogen peroxide. Dilute the drug store stuff to 1/3 to 1/2 strength. If that doesn't work, you can try spraying a copper-based fungicide. They are supposed to kill all bacteria. Don't apply it under hot, intense lighting or it can burn the plant. Good luck.

Here is a link that might be useful: bacterial leaf spot

Question? Are you using natural light. If so your plant is reacting to it's natural cycle. Any natural light.

Thanks for the help Cole_Robbie, they died on me, so I will be starting over with a new organic seed batch I bought instead of the seeds I used last time, which were just seeds I collected from some store bought orange and yellow bells I got from a local health food store. I knew about using hydrogen peroxide to clean my hydroton, but I didn't know you could use a weak solution in a spray. Will be cleaning my entire system this week to prevent any issues in the new crop. I forgot to include my light source. My systems are in one of my spare rooms with a big picture window. I have my tomatos in front of the window(West facing) now because they are too large to put under my lights which are 100w SFL's (1750 lumens per bulb) which I have all my peppers growing under. NFT system just has 4 - 2 bulb 40w shop lights that it uses.

if you've got a system with nothing growing in it, just you a 10% bleach solution to sterilize it.

Hi:

I am seeing it happened on the lower leaves, how did the growing tip was doing? I also see the EC is very low for sweet pepper. When they are young they can handle with that EC, but after maturity, you will need to increase it. You will notice it on the older leaves. Please post what is happening with the next production cycle after disinfecting.