New Grower Brown spot on leaf, not sure the cause

[narmohare]

Hey guys. I have 4 plants going currently. My plant Sadie, is almost done with flower. She's got about 3 weeks left to fatten up, and then she will be prime for harvesting. Recently while checking all my plants, I noticed a brown spot on one of my leaves. I dismissed it as nutrient burn by splash or something similar, and to make sure I didn't confuse myself and could check for new spots, I pulled the leaf off. While checking my plants today, I discovered another similar brown spot on another leaf. Any help will be appreciated. Relevant information below.

Medium: Coco Coir/ Perlite 70/30

DLI: 50, and has been for weeks with no problems

Nutrients: GH FLORA TRIO with calimagic since using RO water, and growing in coco.

Feeding Schedule: GH FLORA TRIO MEDIUM FEED SCHEDULE, Feed with nute water everyday, or for small plants whenever the pot feels less than 50% full of water. Weekly feeding with recharge. 1/2 tsp of hydro guard with every feeding. Was originally using feeding schedule on growweedeasy, but the plans were stunted and showing deficiencies. Turned to current schedule and they recovered well. Always watering to 20% runoff minimum.

Extra Info:
Plants, Sadie included, have been growing well since I switched to the regular GH FLORA TRIO feed schedule. Have seen no issues up until now. Brown spots on 4 leaves max. Could have spilled nutes or something as I am sometimes careless. Wanting to make sure its not an imminent threat to my crop. Included pic of same leaf side zoomed in. Cheers!!

 

[mdabber]

Not that big a deal let's see the whole plant If it's only a fan leaf i wouldn't worry if you only got 3 weeks

 

[mdabber]

@Mañ'O'Green

 

[420autoflower]

I wouldn’t worry at all! Your plants are close to being done. In late flower, leaves start doing all sorts of funny things.

 

[narmohare]

Not that big a deal let's see the whole plant If it's only a fan leaf i wouldn't worry if you only got 3 weeks

Whole plant. Slight nute burn on some of the older growth, made a couple mistakes when starting the plant. Red stems I believe are due to the light, because they've been like that since late veg, and its only on the stems directly exposed to light. You can see green healthy stems in the shade if you look. Could also be because of cold water. Its winter here, and I didn't realize my water temps were about 60 until early flower.

 

[mdabber]

Looks good to me

 

[420autoflower]

I don’t see anything wrong either.

 

[Fermented_Fruitz]

Ya I’m not seeing anything concerning! Those are crazy purple stems and few diff deficiencies can make that happen! Do u by chance have purple stripes running up and down along the main stem?

 

[narmohare]

Ya I’m not seeing anything concerning! Those are crazy purple stems and few diff deficiencies can make that happen! Do u by chance have purple stripes running up and down along the main stem?

Nope no purple stripes up the main stem. Main stem is actually perfect color. That's why I was wondering if it was maybe due to the light or super cold water Id been giving. I love to learn though, so what WOULD cause purple stripes on the main stem?

 

[mdabber]

Nope no purple stripes up the main stem. Main stem is actually perfect color. That's why I was wondering if it was maybe due to the light or super cold water Id been giving. I love to learn though, so what WOULD cause purple stripes on the main stem?

Magnesium deficiency I think