The fuck is going on with this plant

So I’ve posted a few times about this plant/issue and am still encountering the same issue and trying to see if there’s anymore thoughts here.

2 plants, 3 gal fabric pots, 3x3x6 tent with 1 SF1000 (I know it’s not the best amount of light, working on fixing that)
Mixture of FFHF & FFOF, no added nutes, giving 3/4 gal of water per plant appx 4-5 days apart. Watered January 3rd and prior to that was December 28th.
Day temps/Rh: 78~83 73~80%
Night: 72~75 73~77%

So my one plant has had leaf issues for a minute now, started with some curling edges and a few claws. Figured it was nitrogen toxicity starting from the soil, but leaves are getting progressively crunchier/burnt looking. Even the new growth is showing some rusty coloration shortly after emerging.
Is it possible this is all from nute issues in the soil? If so, do I just ride it out or can I do anything to help here?

Also had someone mention it could be related to my light. I had it pretty close and turned all the way up-light is now set to 80% and approx 20” above plants. My other plant isn’t showing this issue so I’m at a loss, sensitive genetics maybe? Last 2 pics are of the other plant for comparison
Any thoughts or ideas are appreciated.

Any ideas?

Seeing calcium deficiency. What are you doing for calcium?

Are you checking pH?

hotrodharley said:

Seeing calcium deficiency. What are you doing for calcium?

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I haven’t been giving anything additional-was under the impression FFHF/FFOF was good enough until flower

PopAndSonGrows said:

Are you checking pH?

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Not for this cycle-I checked throughout my last cycle and it would come out of the tap between 7-8, under the impression the soil would buffer

Username85 said:

I haven’t been giving anything additional-was under the impression FFHF/FFOF was good enough until flower

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Give cal mag. They need the calcium. The effects are more than just spotting.