Crispy leaves not sure why

Milky Weed said:

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They are in promix bx, I ph the water between 5.8-6, the EC is 1.4-1.6 and I’m feeding 7-15-30 right now with gypsum and epsom salt.

They are getting about 60k lux in terms of light intensity so I don’t think they are burning. Any ideas? I’m thinking possibly potassium deficiency but not sure. They are 47 days in flower.

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