Spotting on leaves? help appreciated

[Lebniis]

I've done my share of searching, here is what I'm dealing with. Can anyone tell what this is from experience? It has popped up in the past 2 days.

I'm in coco, the ph of the nutrient solution was coming out 6.8, it's now down to 6.3. I'm thinking magnesium lock out? Any help.. Trying to learn

 

[Lebniis]

Bump, any ideas?

 

[Space Ghost]

kinda looks like Mg... but the tissue usually yellows before going necrotic... I hit them with 2 TEAspoons of epsum salts/gallon ph'd water

Seeing any little critters about? inspect the undersides of leaves near the central and auxiliary main veins...

What's your nute regiment? ppm?

also some more pics would help a lot and include a full plant shot if possible...

and i might try to get the pH of the solution slightly lower if the epsum doesn't clear things up....

 

[DirtDoctor]

looks like a pH issue to me. should be around 5.8 for coco, I believe.