Lighting Questions and questions

[autonoob84]

Hi, I'm just trying to plan a diy led setup for a 8x8ft space. In that 8x8 space there will be 25 plants lined 5 by 5. With the lighting, I have been left with the impression that I will be able to do this grow using 25 cobs, they will be placed on rails of 5 and there will be 5 rails in total.

The cobs will be the almost complete citizen 1812 v6 bought from cobshop.net and powered by a meanwell hlg-320-1050. So in total 25 cobs and 5 drivers. I will attach a paint sketch of the layout so you can visually see it.

Do you think this would work? When doing the math it does not work out with 30-50w per sq ft. But it will be 1 cob per plant, if that even works? Or will the yield be very low. Would I have no option but to be using 6 rails of 6 cobs instead of 5 rails of 5 cobs?

thanks!

 

[BigSm0]

I really hope this helps people understand the difference between autos and photos and why the two should be threated differently when trying to figure out the total wattage or wattage per square foot.

This is also for the round cree, vero and citizen cobs and not the square eBay ones.

https://en.m.wikipedia.org/wiki/Daily_light_integral

For your space of 64sq’

AUTOFLOWER
25 cobs at 55 watts is 1375 total watts.

At 18 hours it’s 24,750 watts per day.

At 24 hours it’s 33,000 watts per day.

PHOTO PERIOD
At 12 hours per day it’s 16,500 watts per day.

Which is not enough. You would ideally want to be at 25-50 watts per square foot. Upper limits and with co2.

At 25 watts per square foot times 64 sq feet for 12 hours per day the total wattage is 19,200
At 50 watts per square foot times 64 sq feet for 12 hours per day the total wattage is 38,400

Photo period plants at 25 watts per square foot for 12 hours per day is much less than the autos get because the lights are on for 18-24 hours per day.

 

[pop22]

Ahh but what is the optimum DLI for autos? And just as with photo periods, the DLI needs vary with Sativa Dom and Indica dom, with Sativas needing a higher DLI, its not as simple as just auto or photo.

I really hope this helps people understand the difference between autos and photos and why the two should be threated differently when trying to figure out the total wattage or wattage per square foot.

This is also for the round cree, vero and citizen cobs and not the square eBay ones.

https://en.m.wikipedia.org/wiki/Daily_light_integral

For your space of 64sq’

AUTOFLOWER
25 cobs at 55 watts is 1375 total watts.

At 18 hours it’s 24,750 watts per day.

At 24 hours it’s 33,000 watts per day.

PHOTO PERIOD
At 12 hours per day it’s 16,500 watts per day.

Which is not enough. You would ideally want to be at 25-50 watts per square foot. Upper limits and with co2.

At 25 watts per square foot times 64 sq feet for 12 hours per day the total wattage is 19,200
At 50 watts per square foot times 64 sq feet for 12 hours per day the total wattage is 38,400

Photo period plants at 25 watts per square foot for 12 hours per day is much less than the autos get because the lights are on for 18-24 hours per day.

 

[autonoob84]

Right, so it's just less light over a longer period of time. 25 cobs at 55 watt is just under 25w per sq foot in a 8x8

 

[BigSm0]

Ahh but what is the optimum DLI for autos? And just as with photo periods, the DLI needs vary with Sativa Dom and Indica dom, with Sativas needing a higher DLI, its not as simple as just auto or photo.

Absolutely right pop. That is a huge factor but I’m basing this off of the recommendations everyone else makes. 35-50 is the norm over on riu. Most importantly based on 12 hours per day. That’s half the hours most run autos which means twice the light an auto would receive at the end of the day. Right?

I’m still trying to figure the ideal wpsf for autos in general. Some people do well with 50 and others do well with 15. I can say that I have run many different wattages over autos and the more I run or closer to 50 watts per square foot the worst the plants look. From experience I used to park my hps and later cobs inches from my photos. With an auto you can see light stress from less wattage 20 inches away.

 

[BigSm0]

Right, so it's just less light over a longer period of time. 25 cobs at 55 watt is just under 25w per sq foot in a 8x8

I don’t necessarily mean autos vs photo @pop22 but this is how it works out.
50 watts per square foot for 12 hours a day is 38,400 watts per day.
25 watts per square foot for 24 hours a day is 38,400 watts per day.

 

[autonoob84]

I've also seen the vero 29's. There's a few kits(sorry bigsm0 I know you're a cobshop guy) with only 4 of them, running each at 90w with a 400w driver.

What's your opinion on vero 29's? 4 vero 29's running at 90w is surely just enough to cover a 4x4 area, correct? What kind of spacing would you use and what kind of design? Also a noob question which I'm sure I could find the answer too but while I'm typing this I may aswell ask it.

Autoflower cob spectrums, what is in your opinion the best?

Thanks for sharing knowledge and helping make sense of this crazy world <3

 

[autonoob84]

Adding more, it would be nice to drop that extra couple hundred on another set of 4 so you could have 5 cobs per driver running each at 70w.

 

[BigSm0]

No need to apologize. I am happy when a cob hits a grow room no matter who its from.

my opinion on the Vero is this. More cobs the better for your plants but not for your purchase price. The good ole flashlight analogy again. If you hold a flashlight at the floor and cover it with your hand no light hits the floor, If you held 2 flashlights and covered one you still have light hitting the floor. More flashlights the better. I am also a firm believer in lower wattages per cob as the intensity is lower/less and more spread out. Instead of blasting certain parts of the plants its better to have a more even coverage. 50 is my ideal.

As far as spectrum goes I thing its the same with all types of flowering plants. 3500k is the best all around spectrum of veg and flower. Adding additional spectrums in may have a hard time blending at lower heights.

 

[pop22]

Glad you brought this up! I've always seen the flaw in mixing cob spectrums. Each cob is concentrated on a specific area, not spread out and blended. so some of the plant get say, 5000k and some of it gets 3000k and a small amount gets a blend from overlap. To be effective, you'd have to use difusing lenses. IMO, mixing cob spectrums is a waste of time. And I've yet to see a mixed spectrum light produce any better than a single spectrum.

No need to apologize. I am happy when a cob hits a grow room no matter who its from.

my opinion on the Vero is this. More cobs the better for your plants but not for your purchase price. The good ole flashlight analogy again. If you hold a flashlight at the floor and cover it with your hand no light hits the floor, If you held 2 flashlights and covered one you still have light hitting the floor. More flashlights the better. I am also a firm believer in lower wattages per cob as the intensity is lower/less and more spread out. Instead of blasting certain parts of the plants its better to have a more even coverage. 50 is my ideal.

As far as spectrum goes I thing its the same with all types of flowering plants. 3500k is the best all around spectrum of veg and flower. Adding additional spectrums in may have a hard time blending at lower heights.