Is This Light Bleaching? Using Cree Cobs ( See Pics thanks)

Getgrowingson said:

Mag deficient. Get some foliar action going on. Quickest way to turn things around with cal and Mag. They are immobile elements. So the plant cannot move them from one part to another. Therefore foliar works best

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Magnesium is actually quite a mobile element. Mag deficiencies typically start at lower leaves because the needed nutrients are being allocated to the new growth. Foliar application works the most efficiently, but is only a quick fix until the ph of the soil/coco has been brought back into range (most likely cause of deficiency).
Calcium on the other hand is quite immobile once it has been assimilated into a new plant cell, as you stated.

Calcium and Magnesium have the same ionic form, and therefor are competing elements during the cation exchange at the root zone. This is why soil/coco Ph is so critical for maximum uptake of both nutrients.

@TimFox

I am using a 450 Watt Go Green LED for a 4x4 Scrog and I am seeing the same thing for my Blue Dream. I have been chasing my tail on either a light bleaching problem or a Cal/Mag issue. Or I am way off and it is something else? I've attached a pic so please feel free to tell me what you think.

I am feeding every other watering, but always add Cal/Mag. I have applied a foliar spray twice with Cal/Mag, one week apart. Has not helped yet for the Blue Dream, so maybe it is a light bleach issue. I have raised the light to 20 Inches, but no help there either.

I am flipping to 12/12 tonight. I should have flipped sooner as my Scrog screen is just about full. I have much to learn for indoor growing!

Here is a link to my post if you want to take a look:
https://www.rollitup.org/t/1st-indoor-grow-from-seed-with-led-cob-cree-cxb3070-gogreenled.887932/