Help me I'm boggled, yellow spots on leaves

So my healthiest plant (AK47 3 weeks into flower) developed yellow dots on the fan leaves recently that I noticed last night. The other AK47 has them too, but barely. It was most concentrated on the lowest fan leaves, which were the original ones when I got the clone. Either way, they were barely getting any light so I snipped them off and inspected them. The spots are very small (like a pen point), and this had me worried cause I feared they were spider mights. However A) they don't move and look like it's the spot on the leaf no bugs B) they're more contentrated around the center line of the blades of the leaves and C) there's nothing on the bottom of the leaves except you can faintly see the spots from the bottom. I suspect it could be some kind of def., but I'm using a full nutrient line that should have all needed micronutrients and the ph is always on the spot around 6.

Anyways, today I noticed more but on the highest fan leaf on the plant.. eek. Any help guys?

Are u giving them tapwater?

Yea, it's not RO water or anything.

Check under your leaves, and what do you see? Any pictures that you could add to this thread would be helpful...

GrowTech said:

Check under your leaves, and what do you see? Any pictures that you could add to this thread would be helpful...

Click to expand...

If you look at the bottom of the leaf with no light behind it it looks perfectly healthy. If you look at them with a light behind them you see the spots that are on the top of the leaf.