Light Burn Issue

[lstkidd420rasta]

Hello GWE community!!

ive been growing for about a year now (thanks to GWE...you guys ROCK!), upgrading from cfls to hps after 4 months. my issue is that i have never been able to place my plants directly underneath the grow light without burning them (yellowing ,spots,nutrient burn, etc.) i have tried everything and found that i can only keep my plants OUTSIDE the grow closet, greatly reducing the effectiveness of the ventilation system, not to mention my grow lights. The plants just cant seem to handle even a small hps light.

The light burn issue first appeared after the upgrade from cfls's to hps.

Setup:
Lights: ipower 400w mh/hps (currently @50% power i.e. 200w)
w/Giantex 6" Air Cooled Hood Reflector w/ Glass Cover
Ventilation: Apollo Horticulture 6" Inch 440 CFM Inline Duct Fan with Built In Variable Speed Controller
Grow Medium - coco/perlite hempy buckets
Nutrients: General Hydroponics Flora Trio + Cal-Mag + Hydroguard (for root health)

Has anyone ever experienced this and how did you resolve ?

[South Sierra Dude]

Picture 3 has burn? I see nothing.

[OzBud]

picture 3 looks alright besides the two yellow leaves but doesn't look like anything serious.

How far between plant canopy & reflector?
are you drawing air through your hood or just out of the closet? If through the hood is the air going through the hood coming from outside or inside the closet? Are you venting the hot air outside or just into the room the closet is in?

I ran a 600W HPS in a 2'x3' cupboard, open batwing reflector, 117cfm exhaust fan venting into room cupboard was in, not outside with 211cfm intake fan that only came on every now and then if temps rose above 77F and didn't have any temp issues at all. it was a winter grow though with temps down to about 25F outside at night

[lstkidd420rasta]

@SSD

those buds you grew are SICK... Great job!!!

Yea at the time she was experiencing a nutrient deficiency (those yellow leaves at the bottom) while simultaneously having some minor tip/nutrient burn, which i figured out by reading a couple articles here regarding what can happen when ur grow lights are too intense.




@OzBud

Your autos are AMAZING... I should be so lucky!!

the tallest plant is only about 10inches after 9 weeks of vegging 12hours per day under hps and 6 hours under 128w cfls in a separate veg chamber. Hps light is 48 inches off the ground for a net distance of 38 inches. i know, welcome to my world lol!

i am utilizing passive intake with exhaust thru the attic to the outside. The hottest the closet ever got during summer was maybe 83 degrees F and that was rare.

Btw, thanks to all who have replied so far. Pay it forward, right?

Peace

[tyler_ hobbyist]

In my opion any temp over 80 should have added co2 like south said. Normal air is 300-400ppm and optium is 1200-1500 (not indorsing or trying to sell any product) but exhale co2 bags raise co2 by 500ppm in a 4x4 space. The yellowing of the leaves is most likely not enough nitrogen at that point of water, if urnew growth is fine leave it alone yellow leaves wount turn back into green. In my opion the 1000w hps should be kept 48inchs if ur plants are autos I have noticed they like more light but if the lights to close u get nute burn and light stress really quick. My 200w led did that at 15inchs (not all leds are made the same). Make sure ur giveing her proper nutes and Temps also what's ur rh (relitive humidity) because the different stages need different amounts and if ur RH is more than 10 under ur plant will be drinking more quickly equals nute burn. I would move ur 1000w hps 48inchs and see how they react u can always lower it a couple inchs if need be. Also autos need more than 18 hours of light a day I run my from seed to harvest 24/0

[South Sierra Dude]

CO2 is the answer

[tyler_ hobbyist]

You are right about the co2 it's best over 80 degrees but still helps in lower Temps as well.

[lstkidd420rasta]

i think you guys may be onto something. Ali i did so far was open a few windows, threw all of them into closet with door cracked open wider.underneath the light, and after 24 hours i think they're looking better already. i'll report back at the end to let everyone know how things went.

Thanks a million...

Rasta out

[NebulaHaze]

How far away are you keeping your light? If you put your hands where your plants are under the light for 30 seconds, is it too hot? As a general rule if it's too hot for you it's likely too hot for your plants.

The curling on the leaves almost reminds me of unhappy roots, or possibly a nutrient deficiency. Have you been checking the pH? Have you noticed any droopiness?

Overall your plants look good!

[lstkidd420rasta]

Hello...and thank you!

Currently i have my 400w hps light (set @50% power or 200w)) some 38in above the tallest plant. i know its best to have an even canopy but i cant seem to find the sweet spot as my plants were unable to withstand being inside the grow closet at all. Add to that fact that each plant can sometimes seem to have different needs. I feel no heat or discomfort with the light being so high up, but still will get leaves showing some type of stress when i do try to put them directly underneath inside the closet where they belong.

THAT BEING SAID, since i cracked several windows in the past few days since making this post, the plants do seem to be doing better as i now have them INSIDE the flowering closet underneath the hps (still @200w). PH is in the normal range (5.5 - 6.5) with rare exceptions. Roots appeaer to be healthy as far as i can see with no algae or slime showing (probably not the best idea to be growing in 2 ltr soda bottle hempy buckets but i figured i'd give it a shot and see what happens anyway lol). In addition to GH Flora Trio I am adding Hydroguard for root health.

About the only time i notice droopiness is in the mornings inside the veg chamber before the lights come on for the day. i customarily will move them inside with the flowering plants where the hps light is located in an effort to save on the ole electric bill. They will remain in there for the first 12 hours of the day, at which time i put them back in the veg box for the final 6 hours of their day while the flowering plants go to sleep for the night.


sorry for the long response but im a fan of your work and wanted to give as much detail as possible. many thanks for all you guys do...

Rasta

[tyler_ hobbyist]

It might just be the light but all the plants seem to look perfectly healty. In the morning when u turn ur lights on your plants will be drooping as they are resting that's normal. How's the growth of the plants? I'm shocked that only 200wats at 38inchs would give u any problems. But if it works do it lol the more light the better (to a point) if u notice 400w at 38inchs is stressing ur plant than ya turn it down but it shouldn't. Happy growing we love seeing updates