Yellow blotches on single plant

sorry for posting a whole thread on this. I really wish the pictures and links on most stickied threads on rollitup actually worked...

The strain is c99. It is one of five plants I have in the same conditions DWC-- nutes are mixed with Lucas ratio at 1.6ec and started at 5.8ph and everyone went to 6.3 fairly quickly and have stayed at that PH and EC The past couple weeks. Is this a boron deficiency? Thanks for any help...image.jpegimage.jpeg
 
Forgot to mention-- daytime temp 75-77 -- night 66-70. Relative humidity between 57-60% all times with a nice fan blowing on them enough that I'm proud of my stems!
 
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