Could this be Sun scald ? Try some shade

Due to overflow holes it is not possible to overfill the reservoir. If the correct soil is used it will not ever be too wet. Al

its ber, i let my swc's almost dry out for my peppers. did you add any dolomite lime to your container mix? over and under watering cause how calcium moves throughout the plant. causing ber. there other things that contribute to it but in your case to wet. when the plant gets older it corrects its self. most of the time.

Just my opinion, but based on what I've read about PVC re leaching of chemicals, I would advise using polyethylene (PE) or some other type of pipe instead. I know at least that in California, PVC has to be labeled as a carcinogen, but I can't speak for other types of plastic.

With miracle grow mix and a full reservoir all the time, it's probably too wet.

Let the reservoir dry out for a couple days before re-filling it.