Late In Flower Issue With Leaves

[OGbushwacker]

I'm wondering what happened with my plants late into flower a lot of the leaves slowly got rusty spots in the middle the black spots then leaves are slowly turning yellow then brown. I want to prevent this for next time it doesn't seem like the flowers are affected but let me know what you think.
-all advanced nutrients
-ec 1.9 to 2.2 when at 2.2 issue began
-temp 79 lights on
- humidity 55 to 60

 

[BioStimz]

The blotching suggests a calcium deficiency.

Looks like you need a little cal-mag.

~

 

[OGbushwacker]

The blotching suggests a calcium deficiency.

Looks like you need a little cal-mag.

~

I use 700 ml per 100 gallons of sensi-cal extra-mag by advanced nuts

 

[OGbushwacker]

I use 700 ml per 100 gallons of sensi-cal extra-mag by advanced nuts

More?????