I hate to contradict my highly esteemed brothers here, but I disagree in some part with the previous assessments.
I see nothing that indicates a Mg-, and if it were a Mg- then giving a foliar, which is fine for just about any age plant IMO/IME, then the foliar applications would have stopped the effects you're observing. Also, you would be seeing yellowing of lowers first, IME.
Growing in coir, and for coir he wants a pH of between 5.8-6.2. I do think you should be letting the pH range instead of keeping it pegged at 5.8.
Two things are going to reliably cause the leaf edges to turn like that, one I've experienced plenty of times and the other I never have and hope I never will. The first is vapor pressure deficit--too hot and too DRY. Lowering temps, or if they're in range then increasing humidity will change the leaf aspect. The other thing that I've seen that causes that, but not experienced myself, are broad mites. If those were my plants, I'd be scoping them very closely, 100x magnification, to rule out anything like broad mites.
Reading your subsequent posts, the VPD shouldn't be too far off in this scenario, but you might want to try raising RH a bit anyway.
I'd be scoping those girls REALLY hard, myself. Because that doesn't look like a deficiency. Yeah... looking at them again, scope those girls. I don't think it's overfeeding, especially at something like a .5-.8 EC (going off my really bad mathematical calculations, I've become accustomed to EC instead of ppm)? I don't think the VPD is too far off, and I don't think it's the media or the feed being too strong, in fact, if they're pale green it'd be a fairly clear indicator they need more food, not less, especially N. It's hard to say with HPS-yellow pix and not knowing whether or not they may be infested with broad mites.