Rust spots and necrosis on leafs

Are you using R.O. water? Did you do a heavy leaf prune lately? Are your EC and pH meters calibrated?

Hey a aron I thought falling both EC and pH means a water change?

Hey grannie. I always add calmag 2.0. This also has N in it. My first run I also had N tox, but this showed by dark green and slim leaves. I use GH Flora Nova tripart. With calmag at a 1:1:1:1 ratio, before I swith to 1:1:2:3 (calmag:grow:micro:bloom) when the buds start forming. I already added 100ml of both calmag and micro (had to add those first) to my new water. Will add 50ml grow and 150ml bloom today. And will add the new solution with water with recommended ratios of nutrients. Am I using to much calmag? It's high in N, and when you say to add a teaspoon. That's a lot less then 100ml LOL

The decrease in EC and pH, as well as the rust spots, are telling you you're using too much nitrogen in your system and you're in lockout - so decrease the nitrogen and think about adding some PK to the solution (along with about 1 tsp calmag) .... she's needing food but not the kind you're giving her. Good luck...

I’d say your pH is off. Make sure it’s in a good range for a few days before proceeding to something else. You may not get rid of the spots you have, but you won’t get any more. Of course it could be other things, but pH is the usual culprit.