Calcium/Magnesium deficiency?

Day 36 Hubbabubbasmelloscope by Mephisto.
Great lakes water only soil in 5gal fabric pot
4x4x6 tent with 4x QB96 V2 elite
6.5ph tap water with 70ppm
Canopy getting around 50k lux
I noticed the weird blotchy yellow on random leaves, including new growth about a week or so ago. Last 2 days, the brown spots have been appearing

I did add 1/2 cup ewc and kelp meal as a top dressing about 5 days ago

Temps are 70-80F with 40-50% RH
I don't water to run off. Usually .75 gal for the 5gal pot

Any ideas?

More likely potassium deficiency.

Yeah, I think you've got the right of it ... looks like she could use a little calmag

hotrodharley said:

More likely potassium deficiency.

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A lot of the leaf stems are turning purple. Some are still green or half fading too

@hotrodharley knows more than me, so I'd take his advice first. Those two deficiencies look super similar to me until the late stages

Gentlemencorpse said:

@hotrodharley knows more than me, so I'd take his advice first. Those two deficiencies look super similar to me until the late stages

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I'm still learning and haven't run into this before lol. I'm at a loss rn and just don't want it to get worse and hurt the final quality/yield

seedstodreams said:

I'm still learning and haven't run into this before lol. I'm at a loss rn and just don't want it to get worse and hurt the final quality/yield

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Have you given anything with phosphorus and potassium yet? If organic give it a chance to catch up. Don’t remove the leaves yet. Watch for increasing damage. And they do demand calcium in early to mid-bloom.

hotrodharley said:

Have you given anything with phosphorus and potassium yet? If organic give it a chance to catch up. Don’t remove the leaves yet. Watch for increasing damage. And they do demand calcium in early to mid-bloom.

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I top dressed with 1/2 cup kelp meal and 1/2 cup ewc about 5 days ago

seedstodreams said:

I top dressed with 1/2 cup kelp meal and 1/2 cup ewc about 5 days ago

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I’m not experienced in using those. Purple is phosphorus deficiency. Spotting is potassium deficiency. Expect magnesium as well considering so treat that as well. 1 tablespoon unscented Epsom salts per gallon of water.

I see kelp meal provides potassium. Check your additives for whatever provides phosphorus. Also cultivate the medium well and make sure water can get into the entire containers worth of medium.

hotrodharley said:

I see kelp meal provides potassium. Check your additives for whatever provides phosphorus. Also cultivate the medium well and make sure water can get into the entire containers worth of medium.

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Thank you! I'll check back in a few with an update

hotrodharley said:

I see kelp meal provides potassium. Check your additives for whatever provides phosphorus. Also cultivate the medium well and make sure water can get into the entire containers worth of medium.

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I reached out to the guy who makes the soil (Detroit Nutrient Company) and he said it's likely due to my lights. She's definitely getting worse fast
I just raised them from 18'' to 20''

Would those deficiencies spread that fast?

The lower leaves look good and green and I'm starting to notice the same thing on 2 of my other plants. Weird yellowing and small brown spots on random upper leaves

seedstodreams said:

I reached out to the guy who makes the soil (Detroit Nutrient Company) and he said it's likely due to my lights. She's definitely getting worse fast
I just raised them from 18'' to 20''

Would those deficiencies spread that fast?

The lower leaves look good and green and I'm starting to notice the same thing on 2 of my other plants. Weird yellowing and small brown spots on random upper leaves

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Deficiency would unlikely spread that quickly unless you have root problems. Unlikely with all plants.

hotrodharley said:

Deficiency would unlikely spread that quickly unless you have root problems. Unlikely with all plants.

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Here's today, still not seeing it as much on the middle/lower leaves