Yellowing, curled up leaves in flower

I’m about 4 weeks into flowering and many of my leaves are very pale…many but not all have developed dark blotches on the interior of the leaf before the tips would curl up and dry out. I expected some leaves would do this in flower as the plant is shifting resources to the buds but I never expected it to effect so many leaves. It started in the lower leaves but seems to have spread to the upper leaves even to some of the buds. I guessed it was a ph imbalance causing nutrients lockout…possibly mag def?. Many purple stems. So I did a flush but I am just worried that it’s too late. After doing some LST-ing, I am happy that I have many colas but they aren’t fattening up much as of yet and I’m afraid it’s because of whatever is going on with the leaves.

I am growing in soil and have been ph-ing my water to about 6.5 after adding the fox farm big bud nutrient solution and testing the runoff to be in the 6.4-6.8 range. Hope I am not too late!

It does sound like a pH issue. Yes, what the pH is now is good but what the pH was before or when all this started is what was important. Hopefully it isn’t to late and your yield hopefully won’t suffer too much. A cal-mag deficiency might be a contributor as this can sometimes show up in flower. I don’t know anything about fox farm but usually most mainstream nutrient mixes make sure you are covered for cal-mag during flower.