I have a similar issue, and it seems I saw somewhere that it is a cal/mag def.......

We use different water, I do not have spider mites, it is not a mold to microscopic exam.

So, I only see in during the last 3 weeks of flower. I am trying Cal/Mag now, but I noticed it really dropped the ph of the water and I had to buffer it first. Next time I give less than the advised I think.
WashougalWonder Reviewed by WashougalWonder on . Yellow Leaf Dots Spreading Completely Over Some Leaves (It's not spider mites) Hi All, I'm trying to diagnose this leaf problem. It's currently affecting almost every plant in the room, some significantly (half the leaves), others totally minor. It doesn't seem to have any pattern: the edge plants (least light, least heat) have it no more or no less than the center plants. I know there are a lot of factors to consider in diagnosing a plant problem, but maybe someone will know what's going on -- once they see the pics and read the post. The pictures show how it Rating: 5