Cannot Identify Disease, but ph is the Suspect

Please help! Just finishing 2 months of veg using same soil (FF) and lite nutes as always but this time I am getting a number of leaves that look like the enclosed pictures. I have tried to identify using the pictures in the forums, but to a newb like me, this looks like MANY things from too little magnesium and/or calcium to too high ph. Only about 10% of leaves have this crud on them, but some are at the top, so I'm worried it's going to continue through flowering.
Please, if you know for sure what this is, let me know so I can fix it. I'm guessing it's ph-related. When I water them, I use 6.8 ph water but when I check the solution that drains from the plant, it's closer to 7.7. Which ph should I go by? Or should I keep lowering the water going in until I can get it to drain at 6.5-6.8 ph?
Thanks in advance for the help.

What are you measuring pH with? Usually, FF is acidic, not alkaline.

Wet

id be flushing them and go from there

id say its a couple problems there...first spider mites..check real close and see if any of those red dots move...and it also looks to be lacking MG..thats why you have curled leaf tips and brown yellowing areas of the leaf that are drying up....get you some lady bugs and start feeding with a more balance npk ratio fert

Although I have never experienced those red tips and dots on the leaves, I would start by lowering the pH of the nutrient solution to around 6.2, at least. Go lower even but don't go below 5.5. I have heard also that a lower pH during veg is beneficial, although I've never tested that theory out as all my solutions are at 6.0-6.2 pH continuously. If the runoff is reading at 7.7 though, that's way too high.

Also, I don't think it's spider mites, as I've had that problem before in a pretty extensive way. That doesn't look like spider mites at all to me. Also, spider mites and other pests tend to be sporadic in their attacks. What you are experiencing looks systematic, not random.