Brown almost black spots on leaves.

[WickedBaked]

Hey all, my G13 Haze is @ 39F and I last watered it with plain pH'ed water. Some of the leaves have turned a very dark brown almost black and I can't tell what the issue is. Is this light burn? I have moved the lights up but I'm not convinced it's light burn.

Heres some info followed by pics, any help is appreciated!

• Barney's Farm G-13 Haze
• Vegged ~80-90 days
• Day 39F
• Coco coir/perlite mix
• General Hydroponics Flora Trio using this schedule + calmag
• Tap water
• 250 watts(from the wall) of LED COBS
• Closet Grow ~ 8sqft
• 200CFM exhaust fan with 120mm fan for intake
• Desk fan for air circulation
• Temps 70-85F, generally ~79F
• Humidity 50-60%
• The last feeding was 3 days ago using plain water pH'ed to 5.8

https://imgur.com/a/Bujdo

 

[Speed of green]

What e.c/ppm are you feeding at?

They dont look overfed, a little mag deficient on some of the leaves possibly.

The large brown spots could be heat or light burn, but i think you would see it on the higher flowers first, im not too familiar with led's and their light pattern.

You can check your runoff e.c and ph to start ruling out variables, Coco doesnt like to be dried out completely, infrequent waterings can lead to nutrient buildup/lockout/nutrient burn.

Hope this helps.
Good luck.

 

[WickedBaked]

While I have not checked the ppm's going in in a few weeks, it was previously around 700-800.

For the last feeding the pH was 5.81 going in and it was coming out at like 5.65-5.7.

I will admit that I sometimes do wait an extra day with watering, if there is any moisture first knuckle deep I'll wait until the next day. I swear I read somewhere that letting coco dry out slightly more can benefit the plant. Something about the plants roots and oxygen/searching for more food.

 

[Speed of green]

While I have not checked the ppm's going in in a few weeks, it was previously around 700-800.

For the last feeding the pH was 5.81 going in and it was coming out at like 5.65-5.7.

I will admit that I sometimes do wait an extra day with watering, if there is any moisture first knuckle deep I'll wait until the next day. I swear I read somewhere that letting coco dry out slightly more can benefit the plant. Something about the plants roots and oxygen/searching for more food.

This is true, you do want the coco to dry down in between waterings especially when the plant is in veg, it promotes root growth.

When i say dry i dont mean completely dry, you want it to be moist.. letting it get completely dry is a problem.

this probably sounds confusing, but i dont know a better way to explain it. hopefully someone else will chime in.