Light stress or Mg deficiency?

lochem

Well-Known Member
Hello fellow gardeners,
Is this young White Widow showing signs of heat stress?
With lights on, my tent is a constant 26-28 C (79 - 83 F) and RH is 64%-74%.
And I do trust my sensors.
Mars Hydro TSW2000 turned down to ~40% intensity. Light was ~ 10” from leaves. Growing in coco.
recommends 24” for veg for that light but they also give measurements for PAR readings at different heights, and I mentioned I am at 40% intensity (because of high temps when running the light at 100%) which is why I was lowering the light.
When I had it at 35-40%, at 24” my WW was stretching....
i noticed there is also a small amount of yellowing on a few of the leaves, in between the veins.
so do you think this is a magnesium problem possibly??

i do use calmag. I also am thinking that I might raise my pH to 6.1 for the Mg to have an easier time to get taken up...I have been pH balancing my nutes solution to 5.5-5.8.
 

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calvin.m16

Well-Known Member
For Coco you want your nutrient solution to be 5.8 PH.

I use the Mars-Hydro TSW-2000 Fixtures and personally I can't use them dimmed they are too weak for plants I'm trying to VEG. I run at 100% and instead fixed my heat problems using air conditioning and keeping airflow. With LED lights you can safely run your temps up to 80 F no problem because the leaf surface temperature isn't going to go up +6 F like with HPS or CMH.

Optimally you should keep your humidity between 45% throughout lifespan to avoid issues like mold/mildew and keep certain pests at bay. I grow 5 different genetics & strains in this climate and they love it. I keep my temperatures between 68-78 F and try to maintain 45% humidity and so far it has worked for years. I've tried higher humidity in veg and its not that helpful unless they're seedlings. Then again though my humidity never goes under 40% and I need to work my equipment pretty hard to hold a 45%.

Those plants look fine, maybe chill on watering a little and give them more light.

I personally hang my TSW-2000 panels 12 inches from the top of the plants @ 100% power.
 

lochem

Well-Known Member
For Coco you want your nutrient solution to be 5.8 PH.

I use the Mars-Hydro TSW-2000 Fixtures and personally I can't use them dimmed they are too weak for plants I'm trying to VEG. I run at 100% and instead fixed my heat problems using air conditioning and keeping airflow. With LED lights you can safely run your temps up to 80 F no problem because the leaf surface temperature isn't going to go up +6 F like with HPS or CMH.

Optimally you should keep your humidity between 45% throughout lifespan to avoid issues like mold/mildew and keep certain pests at bay. I grow 5 different genetics & strains in this climate and they love it. I keep my temperatures between 68-78 F and try to maintain 45% humidity and so far it has worked for years. I've tried higher humidity in veg and its not that helpful unless they're seedlings. Then again though my humidity never goes under 40% and I need to work my equipment pretty hard to hold a 45%.

Those plants look fine, maybe chill on watering a little and give them more light.

I personally hang my TSW-2000 panels 12 inches from the top of the plants @ 100% power.
Thanks for your reply. So....
I can’t run the light at full power- even with removing the hardware from the top of the light with the dimmer, placing them outside the tent, and fans blowing around inside, the temp just gets too hot in there. The tent is 0.8 x 0.8 x 1.8 m. I have 4” intake and a 6” exhaust fan with carbon filter.

man I would love to be able to get down to 68-78 F but with my small tent squeezed into this storage area under the stairs of my house, ventilation is tricky and temperature is very, very hard to keep below 79 F if the light dimmer is any higher than 40%.
By the way I’m using BioBizz nutrients plus a calmag and an enzyme (Canazym).
I went from an inflow EC of 450 microsiemens on my feeds and then straight into 1400+ when I started following the BioBizz schedule and I think that might have given the WW a shock and perhaps a nitrogen surplus and locked out some of the other nutes, particularly Mg.
i should note that the bubba kush vegging right next to the WW in the same tent is not showing any leaf curl. I’ve attached a photo.
 

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Hollatchaboy

Well-Known Member
Thanks for your reply. So....
I can’t run the light at full power- even with removing the hardware from the top of the light with the dimmer, placing them outside the tent, and fans blowing around inside, the temp just gets too hot in there. The tent is 0.8 x 0.8 x 1.8 m. I have 4” intake and a 6” exhaust fan with carbon filter.

man I would love to be able to get down to 68-78 F but with my small tent squeezed into this storage area under the stairs of my house, ventilation is tricky and temperature is very, very hard to keep below 79 F if the light dimmer is any higher than 40%.
By the way I’m using BioBizz nutrients plus a calmag and an enzyme (Canazym).
I went from an inflow EC of 450 microsiemens on my feeds and then straight into 1400+ when I started following the BioBizz schedule and I think that might have given the WW a shock and perhaps a nitrogen surplus and locked out some of the other nutes, particularly Mg.
i should note that the bubba kush vegging right next to the WW in the same tent is not showing any leaf curl. I’ve attached a photo.
Did you get it figured out?
 

calvin.m16

Well-Known Member
Thanks for your reply. So....
I can’t run the light at full power- even with removing the hardware from the top of the light with the dimmer, placing them outside the tent, and fans blowing around inside, the temp just gets too hot in there. The tent is 0.8 x 0.8 x 1.8 m. I have 4” intake and a 6” exhaust fan with carbon filter.

man I would love to be able to get down to 68-78 F but with my small tent squeezed into this storage area under the stairs of my house, ventilation is tricky and temperature is very, very hard to keep below 79 F if the light dimmer is any higher than 40%.
By the way I’m using BioBizz nutrients plus a calmag and an enzyme (Canazym).
I went from an inflow EC of 450 microsiemens on my feeds and then straight into 1400+ when I started following the BioBizz schedule and I think that might have given the WW a shock and perhaps a nitrogen surplus and locked out some of the other nutes, particularly Mg.
i should note that the bubba kush vegging right next to the WW in the same tent is not showing any leaf curl. I’ve attached a photo.

Yeah Mars Hydro lights get super hot they undersize their drivers. If tuned to 100% they put off more heat than my 4 foot 8 bulb 54W HO T5 fixtures.. You may wanna look into better quality stuff to help with those temps and just get a few runs from the Mars. I noticed Mars also make plants eat a stupid amount of calmag.
 

lochem

Well-Known Member
Did you get it figured out?
Oh heck yeah.
i installed an air intake vent in the wall that my grow tent is sitting behind. That fixed almost everything. Running the lights on at night and they are thriving.
I’m in week 5 of flower now.
photos attached
 

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calvin.m16

Well-Known Member
Oh heck yeah.
i installed an air intake vent in the wall that my grow tent is sitting behind. That fixed almost everything. Running the lights on at night and they are thriving.
I’m in week 5 of flower now.
photos attached
Looking good. Thanks for the update. HVAC is insanely important in any indoor grow.
 

lochem

Well-Known Member
Looking good. Thanks for the update. HVAC is insanely important in any indoor grow.
So true.
this grow is my first in coco and my first anything not soil and my first under LED so I’m totally enjoying the learning curve.

almost through week 7 of flower.
check out these happy plants!!5C5A71CB-EA3A-4D32-81EF-DEA653C7D97F.jpeg5C5A71CB-EA3A-4D32-81EF-DEA653C7D97F.jpeg983E59DB-3109-45E9-9FCC-1BEF31DD6904.jpeg1425AEE9-EB4E-487D-BBE2-A35D54A4FD25.jpeg651FCE0B-343F-4906-84C4-0B46F7382C5F.jpeg4EC3176F-EAB4-4D1F-972F-682BC47E52E1.jpeg82B62547-4807-4564-AA80-2873E2A6A266.jpeg
 
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