SOIL Markings on leaves

[FortyNation]

What is going on with this Blackjack auto from seedsupreme? I first noticed it a week or two ago and it seems to be spreading very slowly. However, the plant still seems to be progressing through flower just fine. It is about 8 weeks old as well. The other two plants in my tent look fine and do not have these markings on any leaves. They are Zkittles auto, though.

I grow in a 3x3 with Spiderfarmer se5000, 18/6 lights, and i have a perpetual harvest setup with autos.
Oscillating clip fan and exhaust fan
ocean forest in 3 gal fabric pots
GH flora trio with cali-mag about every other watering or so (after ocean forest nutrients are generally gone after a few weeks or so)

Did I forget anything? Thank you for the advice.

 

[90Gizmo]

Am thinking Cal mag. I know you're giving it but maybe that one plant is a heavier feeder?

 

[Orggrwr]

Might want to check ph also.

 

[Rwise]

When I get these spots I add dolomite lime and epsom salt, my pots are a tad larger, last dose was 2 quarts dolomite and a handful of ES per pot.

 

[SoOrbudgal]

I agree don't feed anything until this passes. Flush it when it's dry just water then give it a healthy dose of cal mag. Those rotten leaf won't get better they'll dry an fall off or take them off. Too much love is what happened, they don't need a whole lot of nutes. Good luck.