Spotted crisp leaves

If your soil is truly pH 4.5, you have serious problems! Growing cannabis plants in coffee cups is like keeping an elephant in a bird cage and akin to plant torture! Giving them a mix of 9-10 different fertilizers and it gets worse - no wonder your plants are unhappy! Giving so many nutrients and in such a small volume of substrate has no doubt caused a mammoth (pun intended!) build up of mineral salts that no amount of flushing will correct without depleting anything else that may be in the cups, however little the quantities. Amending the soil with limestone dust/powder will take too long and be very risky too in such small containers too; the chance of "over liming" is great. About the only thing that I can see to return your plants to some sort of health at this late stage, is to transplant them into bigger pots with fresh soil/substrate. Water them in well with plain water, and only plain water for the next 10-14 days, before even contemplating feeding anything, and when you do decide to feed them, give a mix of 2-3 fertilizers at most, giving a mix of 9-10 again will just cause further acidification of the new substrate. In future, if you are limited for space in your grow area, grow only 1 or 2 plants in DECENT sized pots, rather than trying to grow many in thimble sized torture chambers. The poor roots must be super stressed by now, the soil completely effed and your plants are reflecting this with their sickly and burnt leaves. It is far better to have one or two healthy plants than it is to have 6 tortured and unhealthy plants on the edge of survival. Coffee cups may be (borderline) ok for seedlings, but are nowhere near adequate for flowering plants, unless you are a "plant torturer", in which case I will come and take your cannabis growing license away from you! Seriously though, flowering plants, well, all cannabis plants at every stage, need good room for root growth; good root growth = good plant growth - this is something that can not occur with growing cannabis in coffee cups. Transplanting them may save your harvest and sensible feeding will prevent soil toxicity from recurring. Hope this helps,.......... Organoman.