Light green splotches with dark gray between veins on 3 week old seedlings

Hey all...just popped a few seeds (2 indica and 2 hybrid) and once roots were poking through all sides of the rockwool I stuck them in my high pressure aero system and these 2 indica plan and this problem just cropped up overnight after about 2 weeks.

Anyone know what it could be? The hybrid plants don't seem to have any problems. I can't seem to figure out why this indica is so much more sensitive to *something*

I wish I knew what to adjust or test for, but my plant knowledge is not very great...any advice is greatly appreciated!

NPK is 2-1-3 and the hydrobuddy screenshot shows the other macros and micros.

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Here's the fertilizer mix I'm using, diluted down to 0.4 EC:

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Here's one of the hybrid plants to contrast:

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