HELP! Maybe calcium deficiency?

[Novice]

Attached is a picture of a plant that I have growing in Kind Soil with Coco Loco. I have a 2' x 4' tent with an HLG300L-R spec LED grow light on 50% intensity at about 24". I have watered through the entire cycle with water filtered through a Boogie-Blue filter and adjusted with citric acid crystals to between 6.5 pH and 6.8pH every 4 - 5 days. There are two other plants in the tent with no obvious signs of distress. Is this a calcium deficiency and how can it be corrected? Kind Soil says to not add any nutrients to the grow.

Thanks,
Novice.

 

[OldManGrower]

Could be. More likely yellow spot septoria. https://www.growweedeasy.com/cannabis-plant-problems/yellow-leaf-spot-leaf-septoria.

 

[CaptainWiese91]

You have burned tips on the lowest leaves.
Its getting too much of something. Or else you wouldn’t have the burned tips

 

[Tersky]

That doesnt look like calcium deficiency to me. Looks more like a ph issue but from what you said ph seems to be in correct range. Do you use a ph pen? if so have you calibrated it recently?

 

[D.A.A.S.69]

I used KindSoil an Coco-Loco for quite a few grows, and and kinda liked it, it grows some real sticky-good smelling weed.
Yours looks like root problems to me, but I can't be sure.
Anyway, good luck.