All COB Users - Lettuce Grow Challenge!!

OneHitDone

OneHitDone

Well-Known Member
PicklesRus said:
So, it seems ridiculous to use cxb3590s for lettuce, but I'm struggling trying to figure out what LEDs I should choose for my DIY led fixture for lettuce/herbs...

I think white would be more versatile in the long run, and add some red. What LEDs should we be thinking about?
Click to expand...
Something in 6500K and the consensus seems to be NO additional red for lettuce.
 
muleface

muleface

Well-Known Member
PicklesRus said:
So, it seems ridiculous to use cxb3590s for lettuce, but I'm struggling trying to figure out what LEDs I should choose for my DIY led fixture for lettuce/herbs...

I think white would be more versatile in the long run, and add some red. What LEDs should we be thinking about?

I want to build my own LEDs for my shelving system but honestly just buying some commercial strips would be costlier but zero hassle.
Click to expand...
I'd think at the correct height, with the proper room temperature and lighting cycle a cxb3590 wouldn't be any different than a light designed for lettuce, say like a t5 6.5k. From what i read, lettuce needs 15 mols a day. If you give it too much more then that you get tip burn. I'd think if you could hit that with any light within reason you would be able to grow lettuce just fine.

I'm with you on the commercial strips, to save a few bucks isn't worth the hassle some times.

I would like to get my new lettuce setup running tomorrow. My spourts are ready to be moved from the germination area to their adult home. My point here is that i am using a lot of really low end lights for this, if they grow lettuce well, that might be an option to consider. For a 4x8 area my total light cost is $110.

I'm also going to try some of Robins (www.northerngrowlights.com) Quantum boards. At first for tomatoes, then maybe for some lettuce. From a price prescriptive, they are pretty reasonable. I think he is asking 75 per panel, but you need a driver, and at higher wattages, a heatsink. But say for a 4x4 area, you could get 4 lights, 4 heat sinks and a large driver or 2 midsize driver for under $500. So it comes in at about $1 a watt.
 
muleface

muleface

Well-Known Member
OneHitDone said:
This was an idea I had previously discussed with another knowledgeable member:

What do you think of running 5 small cobs like this
https://led.cdiweb.com/ProductDetail/CLU0261201C1653M2G2-Citizen-Electronics-Co-Ltd/562322/

in place of each 2ft of the led strips. 10 Cobs total on a 4ft bar for growing greens, lettuce, veg?

Was thinking just slap them onto a 1" heat sink with some thermal adhesive and solder them up.
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so a 10 pack get you 4650 lm for about 20 in lights, not sure what a driver would run you, but a cheap import, maybe $10??? wiring, heatsink, braces, you think 50 a light?
 
OneHitDone

OneHitDone

Well-Known Member
muleface said:
I'd think at the correct height, with the proper room temperature and lighting cycle a cxb3590 wouldn't be any different than a light designed for lettuce, say like a t5 6.5k. From what i read, lettuce needs 15 mols a day. If you give it too much more then that you get tip burn. I'd think if you could hit that with any light within reason you would be able to grow lettuce just fine.
Click to expand...
The issue here I don't believe to be so much related to intensity as it is Spectrum. Cob is not anywhere near as close to FULL Spectrum as a T5 or HID light source.
I am still awaiting some gorgeous COB grown lettuce to be demonstrated here so I can eat crow :lol:
 
PicklesRus

PicklesRus

Well-Known Member
muleface said:
I'd think at the correct height, with the proper room temperature and lighting cycle a cxb3590 wouldn't be any different than a light designed for lettuce, say like a t5 6.5k. From what i read, lettuce needs 15 mols a day. If you give it too much more then that you get tip burn. I'd think if you could hit that with any light within reason you would be able to grow lettuce just fine.

I'm with you on the commercial strips, to save a few bucks isn't worth the hassle some times.

I would like to get my new lettuce setup running tomorrow. My spourts are ready to be moved from the germination area to their adult home. My point here is that i am using a lot of really low end lights for this, if they grow lettuce well, that might be an option to consider. For a 4x8 area my total light cost is $110.

I'm also going to try some of Robins (www.northerngrowlights.com) Quantum boards. At first for tomatoes, then maybe for some lettuce. From a price prescriptive, they are pretty reasonable. I think he is asking 75 per panel, but you need a driver, and at higher wattages, a heatsink. But say for a 4x4 area, you could get 4 lights, 4 heat sinks and a large driver or 2 midsize driver for under $500. So it comes in at about $1 a watt.
Click to expand...

The one set of commercial grow strip lights I'm looking at are rated at 2umol/j and a 4x4 space 4 fixtures at 200umol coverage is 541$ free shipping with 5 year warranty.

The second set of lights may be around the same efficiency and price but instead of being white will be a mix of white red green and blue.

Each strip is about 54w. The coloured ones are made with a really good heat sink and come with 10 year warranty. They also come with a 90 day money back garuntee.
 
PicklesRus

PicklesRus

Well-Known Member
OneHitDone said:
The issue here I don't believe to be so much related to intensity as it is Spectrum. Cob is not anywhere near as close to FULL Spectrum as a T5 or HID light source.
I am still awaiting some gorgeous COB grown lettuce to be demonstrated here so I can eat crow :lol:
Click to expand...
Wait cobs are full spectrum aren't they? A cob of the same temp as any other LED performs the same doesn't it? Cobs of the same temp as a quantum board for example

What we need is a comparison:

Cob 3500k
Cob 4000k
Cob 4500k
Cob 5000k
Cob 5500k
Cob 6000k
T5
Cmh
 
PicklesRus

PicklesRus

Well-Known Member
pinner420 said:
Mine is non ag rated just a 9w house hold 4k.
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Oh, you might not have an equal amount of light hitting the plants the. It doesn't seem to be a fair comparison. 9w a19 LED at most is 850 lumens but maybe less compared to 2000-4000 coming off the t5s.
 
OneHitDone

OneHitDone

Well-Known Member
PicklesRus said:
Oh, you might not have an equal amount of light hitting the plants the. It doesn't seem to be a fair comparison. 9w a19 LED at most is 850 lumens but maybe less compared to 2000-4000 coming off the t5s.
Click to expand...
I would bet $ that the led bulb is putting a higher lux reading to the plant than his T5
 
OneHitDone

OneHitDone

Well-Known Member
muleface

muleface

Well-Known Member
OneHitDone said:
I wish all of the led and Fluorescent fixture manufacturers would offer data like this.
Basically we would need 1 of these modules per nft channel or row of heads about 4" above the plant canopy

https://www.transcendlighting.com/uploads/2/4/2/3/24238850/infinity_linear_flyer__1_.pdf

My bad, they even have application info taking overlap into account
https://www.transcendlighting.com/uploads/2/4/2/3/24238850/lighting_design_guide_infinity_rev1.pdf
Click to expand...
that is great info!! wow! i got it at 11:58 CST, so it was an early Christmas present by 2 minutes.

to go even further, check out:

http://www.convertunits.com/from/umol/to/mols

then take the mols number x60, x60, x24. so...

200 umols = 0.00019999999999999998 mols
x60 = .01199999999999
x60 = .71999999999999
x24 = 17.279 mols per day

so for lettuce you need like 15 mols a day, so you would need to run the lights for 21 hours, with 3 hours off. But i might run then for 21 hours on, then 8 off and so on.

But for 400 umols
400 umols = 0.00039999999999999996 mols
x60 = .02399999999999
x60 = 1.4399999999999
x24 = 34.5599 mols per day
so you need to run for 11 hours, then off for 8 or so.

I am not really sure on the down time. again, something to experiment with...
 
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