Help a Lass out, purplish brownish splotches

Ok I just checked on my plants and I HAVE A PROBLEM.

My plants are 53 days old, and 17 days into bud in 3 gl pails. They are taking more water more often, We went from 3L every 6 days to 4L every 5. Yesterday I watered full feed with Big Bud(since you only use it 3 weeks and it cost so much and I have so much extra) The carbo load, Cal/Mg, and the three part nute system. I'm just using their lite feed though. The pH was at 6.5 going in and soil pH is 6.5.


One one of the 4 taller plants, 2 fan leaves are affected. It starts at the tips and is inbetween the veins. It turns splotchy dark puplish green then affected area contorts as it curls up and dries dark green, not much different than the original green, but crispy.

Update now at 56 days, 20 in flower I've noticed one more of my Affs has this, same area of the plant. A northern has the same pattern too, in the middle of the plant, large fan leaf except because the leaves are darker the splotches look brown. The plants are just drying out now and will probably be watered in the net 2 days, the last time they were watered was 4 days ago. I'm not sure if it is a def or toxicity, so I'm not sure which way to adjust my nutes.

Here is my nute recipe, just type 14L in the resivior size. I'm using Grow, Micr, Bloom, Cal/Mag, Carboload, and BigBud
Nutrients | General Hydroponics | Hydroponic Fertilizer Supplies

Any ideas on what this is? Please help.