Not sure the deficiency. Please help.

I'm not the best at determining deficiencies so a little help is a appreciated. This is my White Widow in her 4th week of flower. She is in ocean forest soil and has been receiving fox farm nutes once a week at 3/4 strength. She is under a 300W LED light about 18 inches from canopy. I have checked PH and it is 6.8 so no worries there. The leaves are turning a pale color very slowly and then crisping afterwards.
This is only happening to the larger leaves and I haven't seen it in the smaller leaves yet but hope to cure before that happens. One thing to mention: the temps range from 78 to 86 F. Humidity is between 46% and 38%.

Please help!!
 

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