Is this Nute Burn, Heat Stress, or an N def

[WarBux79]

Hi guys, I need some help solving a problem. I am not sure if this plant is showing signs of heat stress or perhaps nute burn. I am leaning towards heat stress because I am only seeing the problem on the plant that is directly under the light but would like a 2nd opinion. I am hoping this heat stress is caused from the light being to low and not because of the temps in the tent being too high.

I am growing in a 3x5x8 tent. I use an 8 plant Aeroponic system w/ 6 plants in a 10 gallon reservoir. The reservoir temps are kept at 69 F. I am using Sure To Grow and expanded clay balls as my medium. The lighting is a 600w air cooled HPS lamp and is kept 10-15 inches above the plant. I am using a hot spot diffuser on the light but I dont know if these things even work. The temps in my tent run a bit high. The temps in the tent hover at about 88-90 F during the day the ambient room temp that the tent is in are 78-80. My exhaust fans keep the temps under 90 F in the tent at all times. I keep the CO2 levels at 1350-1500ppm. The RH is kept at 55-65. I am using Advanced Nutes Connoisseur 2.35+ for flower. I am 15 days into flowering @ 1110PPM PH is kept between 5.45 - 5.65. I am unable to get the temps in the tent any lower because adding a seperate AC is not really an option.


This is my 2nd time growing with HPS.

 

[WarBux79]

im 90% sure this is heat stress but would still like a confirmation.

 

[420pharms]

Its good that you have c02 it helps the plant grow and survive at higher temp. your damage is minimal to me and could be heat related I dont do well with pictures. I might try 1800-2000ppm c02 for temp. I run with 800-1000ppm at 70-75deg, 1000-1500ppm at 75-85deg and when I really want to set grow speed record i will run 1800-2000ppm at 90deg all during light cycle I deplete during dark cycle and first hour light, to keep stoma from becoming lazy and useless

 

[WarBux79]

Its good that you have c02 it helps the plant grow and survive at higher temp. your damage is minimal to me and could be heat related I dont do well with pictures. I might try 1800-2000ppm c02 for temp. I run with 800-1000ppm at 70-75deg, 1000-1500ppm at 75-85deg and when I really want to set grow speed record i will run 1800-2000ppm at 90deg all during light cycle I deplete during dark cycle and first hour light, to keep stoma from becoming lazy and useless

Yea pics sometimes make it harder to properly ID damage/stress. I dont want to let any damage get out of control. My reasoning behind thinking its heat stress is because I change my reservoir every week and just top off with water as needed between changes. This damage happened about 36 hours before a reservoir change. Nute burn would be more likely to appear right after a res change due to the elevated PPMs. I didnt know there was any value to having Co2 levels over 1500ppm but on your advice I increased it up to 1800ppm and might raise it higher in a couple days. I lifted the light up some yesterday and the damage hasnt gotten any worse so I went ahead and changed my reservoir increasing my PPM by 200. Other then that bit of damage they look healthy.

 

[420pharms]

cool sounds like your doing real good, i dont think plants eat much c02 after 2k ppm. I do get very fast growth and so should you so get ready to bend or what ever, I hope its as fun for you as me good luck i look forward to seeing your buds in a few wks