Stumped on the problem

So I have honestly spent a good 3 months trying to find this answer and have even taken samples to garden stores. Yet, I cannot for the life of me figure out the issue with the reaper. It is in a 5 gallon and I use the standard Masterblend trio plus added silica. I check PH daily and do my best to keep it around 6.0 and top off with PHd tap water that is dechlorinated between the full change every 2 weeks.

It did have a pretty good aphid infestation that I won, but this leaf issue predates those little demons. The other peppers in the grow area do not have this issue, just the reaper and this is the only one that I am growing. The issue starts as a couple small ones and the leaves are nice and green. Left over time the spots increase in number and eventually the leaf will fall. I have taken to just clipping them when I see them. Over all I would say maybe 5% of the leaves exhibit this behavior.

I have seen anything from pepper leaf spot to aphid induced disease, but nothing picture wise that is at least similar to what I am seeing.

I truly appreciate any help any of you may be able to provide!

 I've never seen this type leaf spot disease that's infecting your Reaper.
Can't opine with certainty as to what type, but if you have a local agricultural extension office nearby, they'll diagnose and confirm whether it's viral, bacterial, or fungal.

Good chance it's fungal disease and treatable, as it's not displaying the symptoms of bacterial or viral leaf spot disease..
Get it checked out and possibly save it. Or start afresh with new plants?

Could it possibly be overfed/ watered?

I appreciate the replies.

The plant is in a dwc and I use the standard 12/12/6 mix per 5 gallons and just top off till change. I am not against using less, I think more than anything if this is a result of me I want to learn and change.

I have tried garden stores but hadnt thought about an ag office, Ill look into that.

As for starting over, that will be this fall. For now I am growing these inside and come spring I will move everyone outside for the summer and let them go at the end of the season.

Here is a picture of her from last month just because