Colour of leafs

Increase air circulation around tent, keep humidity below 50% if you can at rootzones. Try make a negative pressure within your grow space, calculate your cubic feet of grow space and get a inline duct fan with 2x the cfm rating, cubic feet per minute. We want to completely empty the tent in 1 minute or less. Every 10 minutes or so. Constant states of change are good, Stagnation bad. Just my 2 cents. Hope you get your ladies back I shape soon, best of luck.

It's reaaaaaaaly hard to judge without exact and precise details. Looks like 1 plant is bad, others ok? Odd it would effect one not others which makes me think its more environmental than it is to do with feeding, only symptom is when you water more it gets worse ..just the corner of tent that receives the least air circulation. Rootzones of one plant get just that little bit less fresh air, stagnates over time, if you water a too much without completely drying out your medium you are asking for problems. Looks like fungal/bacterial problem within the rootzone imo Try not focus too hard on ph specifics or keeping it precise. Ph is a spectrum like all things, different nutrients uptake at vaaaaaaaaastly different levels between 4.5-7 ph, although every strain comes with a preferred, the plant itself will change the ph of the soil as it leeches and photosynthesises. This is outside of our control but is a very natural part of the process. I would highly recommend watching Bruce Bugbees YouTube video on the 9 cardinal rules of environment for cannabis cultivation. Wealth of lecture grade knowledge for free.