Need some help please

So am I plant is seemingly struggling not liking something there on Sensi grow 18 and 6 on 500 watts right now they were on 750 but I had to drop the wattage because as you can see it was burning the plant but it was the only plant that was burning so I'm still a little confused I don't understand what the spots are I thought they were septoria but I was told they were not so I'm at a loss and don't know what else to do they're getting Sensi grow a + b every two to three waterings and it doesn't seem to be getting any worse or better what am I doing wrong I have good ventilation and I have a good fan going it just just all of a sudden stalled out I did spray it down a while back with some fungicide but I sprayed all three down only that one turn colors and now won't grow so I'm not really sure what's going on

I don't Think it's burnning but I could be wrong some kind of immobile nute deficiency

are you using cal mag?

I' say cal/mag is missing. A touch too wet also. Just my opinion. Peace.

Why is cal mag? I use sensi grow a+b

Simplefireman59 said:

Why is cal mag? I use sensi grow a+b

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What fungicide did you spray with?

Cal mag is a supplement you don't get everything you need in the a and b anything it's juat a base and depending on strain you will eventually run into an issue.

I use Cali magic by Gen hydro

You said there getting a and b every 2 to 3 waterings? Have you been using straight water in your coco inbetween Feeds? That could be your problem