Can someone tell what nutrient problem my plants are going through

Hey for about a week now my plants have been showing brown spots on their leaves. They are appearing on older and bigger fan leaves only . Surely someone here is familiar with this presentation and can school me on what’s going on? My plants are currently on day 36 of flower.

I'm 95 percent sure thats a potassium problem.

Toxicity or deficiency

Mediclove said:

Hey for about a week now my plants have been showing brown spots on their leaves. They are appearing on older and bigger fan leaves only . Surely someone here is familiar with this presentation and can school me on what’s going on? My plants are currently on day 36 of flower.View attachment 4799872View attachment 4799873View attachment 4799874View attachment 4799875View attachment 4799876View attachment 4799877

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If its coco than I would say Calcium, if its soil than probably lockout... can you provide more info about your grow?

Slightly... (1) under watering, (2) over feeding, (3) needs more P!

1. When the root zone repeatedly receives less moisture than it needs, plants will build up "cuticle" to slow down their evaporation rate, to retain water longer in their leaves, because they are not getting enough from their roots!
2. burning, from the tips moving inward.
3. yellowing veins, random yellowing polka dots that turn orangish brown overtime forming in a leaf in-between each leaf vain area!

Nuteburn/lockout, long spindly, pointy and burnt tips with other deficiencies = nutrient lockout from to high total amount of salts.

I usually do a good flush at week 4 in soil just to reset everything and getting back to optimal nutrient ratio.