Is this Leaf Septoria?

Everything was fine until flowering started a couple weeks ago. The yellow spots started and now turning brown. This plant is in the same FFOF/HF mix as my last grow which didn't have this issue.

I have others that are still in 1 month into veg and all currently look ok. Most are in the same mix.

Water is RO w/ CaMg add and ph 6-6.5 range. I don't know the soil ph.

If this is the issue, what good solutions do I have for the flowering plant? Looking at GWE, the solutions mentioned you don't want to get on the buds, and that could be an issue when treating it.

Sorry for the lighting making it extra yellow.

Not leaf septoria.

What have you been feeding? Problems tend to show up once flowering starts.

Been feeding Black Magic all purpose fertilizer. I used it with my first grow also, but didn't have this issue.

Plants are Auto's. I'm using 3g pots. I water ca/mg only until they have been in the pots 4-5 weeks. Then add 1-1/2 tsp fert every 2-3 weeks.