CMH / QB288 / QB120 / SB240 / VERO 29C comparison...

nfhiggs

nfhiggs

Well-Known Member
Danielson999 said:
Lumens/watt is very basic though. What good are lumens a watt when some of the lumens are useless to a plant? My 1750K cobs are horrible lumens/watt but they do nothing but whisper sweet nothings into my ladies ear all day long. They're probably 95lumens/watt or so.

Anyway, if you want to judge a lights value for growing herb you'd be better off using umol/j measurement.
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There are no "useless" lumens to a plant. There is not one single part of the visible spectrum that they cannot use.
 
CobKits

CobKits

Well-Known Member
ganjamystic said:
I did just notice there aren't conversion factors on that page for led.. just for fluorescent, hps, de hps, mh, and cmh... so even though the PPFD of 315 watts of 110lm/w cmh in a given area can be estimated by using that chart, the only way to know how that compares to the PPFD of 315 watts of 150+lm/w led in the same area would be to actually test with a PAR meter I guess...
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1. that page is old when led wasnt as common
2. leds all have different spectrums so it would be hard to have a single conversion factor
 
ganjamystic

ganjamystic

Well-Known Member
CobKits said:
1. that page is old when led wasnt as common
2. leds all have different spectrums so it would be hard to have a single conversion factor
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even on that chart there is one factor for 3100K cmh and another one for 4200K cmh and one for se hps and another one for de hps... I wonder if there are conversion factors out there somewhere for 2700K, 3000K, 3500K, 4000K, 5000K led...

but either way, I just need to get a PAR meter at some point...
 
CobKits

CobKits

Well-Known Member
ganjamystic said:
I wonder if there are conversion factors out there somewhere for 2700K, 3000K, 3500K, 4000K, 5000K led...

but either way, I just need to get a PAR meter at some point...
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you can figure it out, you need to have an actual spectrum for the chip and digitize it to determine QER
 
Rahz

Rahz

Well-Known Member
ganjamystic said:
@CobKits do you have these values for the cxm22s?
@Stephenj37826 ..for the qbs?
@RainDan or @Rahz ..for the vero29s?

and does anyone know roughly the PAR of a 315W cmh and what the average PPFD would be in a 3x3?
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For Vero 29 just download the product sim from Bridgelux. It provides umol/j for most spectrums at 25C. To get an accurate umol/j at other temps just use the LPW for 25C and extrapolate for other temps.
 
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