leaf burn, oh no you don't

[GreenUnity]

Hi guys i need some help, i'm on my 4th week of flowering and i'm seeing burn marks on some leaves.
I think it could be nutrient burn but not quite sure..any ideas?

nutes- advanced nutrients Grow/micro/bloom ph perfect+ Tarantula
medium- Sunshine mix 4
feed once a week, 800-1000ppm

 

[GreenUnity]

great

 

[SeedLab]

How hot is the room, looks a little heat stressed.

 

[kodiak60]

I have a similar problem, using Advanced Nutrients' ph Sensi Grow with B-52, 4 weeks' full vegetative growth, hydroponic. Strange thing though, it's only happening on ONE plant, and just a few leaves of that plant are showing similar burn pattern as OP. There are other plants, different strains, not showing the burn pattern, on same set-up, and one plant that is same strain, but strictly in soil, so on water, water, nute program, and it's not showing burn pattern, either. The soil plant is taller than the one showing the burn pattern, so it's closer to the MH light than the one showing burn pattern. I just raised the light last week because the soil plant was getting tall enough to warrant the raising, but the hydro plants aren't too far behind in height (4-5 inches behind), because they were started later.

Any suggestions as to what may be causing the burn? I have the light air-cooled with a 400 cfm fan ducted out of the grow room, as well as a squirrel fan to circulate air through the room, in the unfinished basement, so it's definitely cooler than the rest of the building! I don't think it's heat-related.

 

[Lurch Farmer]

I have not had this issue after changing to led.
I use A&N senci in a DWC system.
how far from the plant is this air cooled light?
do you foliar feed?
what is the humidity of your room?
what are your room temps?
where are your circulation fans in relation to the
If there is any kind of moisture on the leaves at lights on , the water on the leaves becomes a magnifying glass there for burning leaves.
You would get more responses if you started a journal.