Reaching out for some help here with a sickly plant

[Nev]

The back ground here is four GG4 auto plants growing in organic soil with Geoflora nutes in a 2x4 tent and a Marshydro SP3000 led.
The plant in question is 41days and on GF bloom now. From day one plant has been slow and always lacking to keep up and never looking happy.
The plant for a couple weeks now have shown rusty looking fan leaves at the bottom. I removed 2 a couple weeks ago now there are 4 at each corner of the plant.
I‘m hoping someone can look at the pictures and maybe advise of a direction or solution.

Thank you

 

[Emilya Green]

looks like a magnesium deficiency... the first one I have seen with GFN.

 

[Nev]

looks like a magnesium deficiency

Thank you. This plant is 1 of 2 that also had a bout with the yellow leaves early on. Then it started this. I foliar spayed then with an Epson salt solution for a week or so during the yellow period. Then just last week they were all watered with an ounce per gallon of Cal-Mag plus.
I kinda blame this on the genetics but seems I should be able to combat this. It has me puzzled and I’m searching for any solutions.

 

[Emilya Green]

Keep up with the calmag... once a plant has shown it has a higher than average need, it rarely goes away. At least now the damage is not spreading. Damage from magnesium deficiency is permanent, so don't expect those spots to go away, just look for it not to spread.