Hello T'Mater,
I'm not familiar with the the
growing medium your using, so I don't know how saturated it gets. But I don't think your 15 minute on cycle needs to be changed to a shorter time. If the growing medium is still too wet before the next cycle begins, I would just stretch out the time between on cycles.
My first thought is that it certainly takes a few weeks for plants to recover and that you should be patient. However looking at the pictures you posted I see quite a few leaves with brown edges, and it looks like the one leaf is definitely becoming abnormally yellow. So my first thought there is a possible
nutrient problem. I don't remember what
nutrients your using, or how you mix them. Though I also don't know if it's just lighting in the pictures, or if some of those stems are browning as well (which could also be a nutrient problem), but I looked up the Late blight on tomato's for some images to compare with, and have seen images of dark brown lesions on stems as a symptom of Late blight.
Here is a link with many images you can compare with, as well as how to distinguish late blight from other diseases and disorders with similar symptoms:
Disease photos - Vegetable Pathology - Long Island Horticultural Research & Extension Center
I don't know much about late blight, and I would feel uncomfortable saying your plants have it. But from the little I read about it late blight is caused by a fungus, and damaged plant tissue can't be controlled. you should be able to see the fungus with close examination of the leaves and stems if that is what it is, or even any other fungus or mildew either. I don't remember if you started those plants from
seeds or not, but I would start some new seeds if so just in case. If you do determine it is a fungus/mildew disease, I would CAREFULLY pull the plants as soon as possible, place them in sealed plastic hefty bags to prevent as many spores from spreading as possible. Then clean an sanitize the entire system, as well as spray the entire greenhouse (inside and out) with bleach water a few times before replanting a new crop. I would also probably spray the whole greenhouse, as well as new crop with a fungicide too as a preventative measure.
P.S.
Keep us posted