"The claw" and discoloured leaves 3 weeks into flower?

First time grower here, lately ive noticed some of the lower leaves sort of changing from dark to light green? The plants are master kush and have always been pretty dark but as of the past couple days the light greens appeared. I have a ph meter and ppm unit, i always balance the water. I lowered the light a little last night. Would think if that had some effect on the curl it would taco not claw.. wasnt really looking for the claw last night so not sure if it was there before light change. They get two waters and then one feeding about 3-4 weeks of flower time left for these guys. Help pleasee!!!!

Go easy on watering also check nutes level or history about strain she might or might not be heavy feeder or drinker

Gdp1 said:

Go easy on watering also check nutes level or history about strain she might or might not be heavy feeder or drinker

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I usually let the pots dry out completely , (stick my finger 2inches in the dirt and pick up the pot as test) looking at photos online im thinking possible magnesium deficiency? Ill check the run off next time i water.

Well that was my next solution .in the process of grow star pupil and it did exactly same thing couple of weeks ago and solutions was magnesium after I let pots dry out and noticed no differences even though strain info said she not a heavy drinker