BLACK DOG LED

canadian1969

Well-Known Member
video is a bit dated but most of the commercial fixtures have been in the 1.1-1.5 umol/J range for last few years. most good cob lights (diy and prebuilt) are 1.6-2.0 umol/J at system level

Can you explain for us the calculation you use to get to a umol/J value from a starting point of PPFD (mole/m2/s) ?
 

Rahz

Well-Known Member
Can you explain for us the calculation you use to get to a umol/J value from a starting point of PPFD (mole/m2/s) ?
umol/j is a comparison between light (spectrum & radiant flux) and input wattage. You could work backwards from PPFD provided you know the space the lamp is in to provide a specific PPFD along with the wattage. For instance, if the PPFD in a meter is 1000 the PPF is 1000. If wattage is 500 then umol/j is 2. If PPFD in a 4x4 = 1000 then 1000 / 10.7 * 16 = 1495. If wattage is 800 then 1495 / 800 = 1.87 umol/j

The catch is the PPFD must be measured out for an average over the whole canopy. More typically the PPF data (from an integrating sphere/datasheet analysis) will be used to estimate the PPFD in a particular space (PPF / sqft * 10.7).

What will give a wrong answer is to take a spot reading and calculate from there. Many LED fixtures advertise a spot reading as PPFD... which is technically correct but I'm going to guess most people don't care what the PPFD of a 1 inch square area under their lamp is. It's deceptive advertising.
 

bigcountryfab

Active Member
I know this is an older thread.....but. I've watched Blackdog yield over two and a half pounds in a 3 x 3 tent....I wouldn't call that flashy presentation. LED's have their place. I personally like CMH. A shit ton of heat but also a shit ton of spectrum and output which really plays nicely in a dialed in room. And sorry, cob don't cut it for me. I've done isolated tests and found that even though cobs can create similar yields, the rate of growth and the finished product are not what they are under a well designed blurple light or a cmh light. The missing spectra are problematic in certain circumstances.
 

BCBLondesLEDGrowLights

Well-Known Member
black dog phytomax 2 1000:
$2279 USD
total ppf: 1602
btu: 3581
actual watts: 1050


Gavita 1000 de hps
$400 usd
total ppf: 1614
btu: 3600
actual watts: 1060

Black dog LED are the biggest pieces of shit in the industry.
 

bigcountryfab

Active Member
black dog phytomax 2 1000:
$2279 USD
total ppf: 1602
btu: 3581
actual watts: 1050


Gavita 1000 de hps
$400 usd
total ppf: 1614
btu: 3600
actual watts: 1060

Black dog LED are the biggest pieces of shit in the industry.
I'm amused that your avatar and name are an LED advertisement as you dis LED technology. Gotta plug your company. You people that get in these forums and talk shit about a company that makes good reliable equipment (although overpriced), just to try and boost your own ego are something else. Also I do not work for Blackdog. I can't afford that either. lol
 
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