Plant Leaf issues

Anyone have any idea what this is? Day 12 flower..PPM's 814 runoff, PH 6.6 Using Mills A+B, Calmag, Bigbud. Nutrient PPM's 750.
This issue happen on my last grow too. Was able to finish grow but buds suffered in size and denseness. I"m using Two 300w LED full spectrum, humidity at 55-65%, Room temp never gets over 78f. It kinda looks like Mag deficiency? But my nutrients are on spot so I it has to be something else? I've cleaned the room after my last grow. Sanitize walls, floor, pots, tools etc...

Would love to have a grow cycle with with green lush leaves throughout. My last grow was so ugly I didn't want to show my friends

Smokeweedeveryday!

814 seems kinda low in flower to me, in one of my grows by 12 day's into flower I was feeding 1400. It does look like Mag deficiency or phosphorus. Do you have any burns on the tips? The picture is really blurry.

No burns on tips...seems to start on lower fan leaves...first light yellow spots then the yellow turns brown and starts to spread.

The new growth is it the same way? Your plant will divert a lot of its energy into new growth and swelling buds making the leaves that aren't getting light die off I usually trim the bottom leaves that are not getting any light.

New growth is is fine..seems to be the older fan leaves...this is the latest pic of one of the plants...Its a sativa with lots of High and low stress training..trying to stop the stretch and ended up with this monster

Problem is these spots are mobile and are starting to show up on other parts of the plant

You think i should bump up my Nutt PPMs?

If new growth looks good then it could be an older issue, for sure bump your Ppms I don’t know what everyone else runs in flower but by this time I was watering at 1400 ppms and if I read my journal right the watering after that I was at 1700. I wouldn’t go straight to 1400 ease your way there maybe do 1000 and so on so forth watch for tip burn.

Gave them Calmag and NPK boost 24 hours ago...seems like the color is coming back...cant believe I'm having low Nitrogen issues in Flower. But I guess when you have one deficiency it causes more with other salts. My 4th grow and I feel like I've learned nothing
Thanks for the cheat sheet and advice sir