• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

COB efficiency Spreadsheets

JorgeGonzales

JorgeGonzales

Well-Known Member
resinhead said:
Alright. You guys are throwing a lot of fancy lingo down and obviously know what your talking about.
Could I get away with rocking 3 of the 300 watt 6 cob timber fixtures in a 4x8 tent? Or will I need 4 or 5 kits? I don't understand all of the conversions.
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That's about 774 PPFD :)

You could definitely "get away" with that.
 
C

churchhaze

Well-Known Member
JorgeGonzales said:
PAR watts is an approximation, photon flux is the exact number.
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Photon flux can be just as misleading as power can be. If you don't believe me, try growing with only 660nm leds at a high ppf and see what happens. It's the exact same reason why power doesn't tell you the whole story. Someone could be growing with all 430nm leds and have good power, but low ppf. It really doesn't matter which you use.. you need one of them PLUS spd or you can easily be mislead by either if you're not also given SPD.

When faced with a choice of 2 numbers that tell you the exact same thing (spd constant), I will choose the one that actually relates to how much energy it's going to cost me.
 
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T

todd86

Active Member
All above my head,

My 8 x CXB3590 3500k CD 72V with HLG 185 C700B driver

Will this put out more plant useable light than my 600 watt hps running a Phillips son t pia bulb??

Thats what i need to know.

To all the gurus

Thanks in advance.
 
testiclees

testiclees

Well-Known Member
todd86 said:
All above my head,

My 8 x CXB3590 3500k CD 72V with HLG 185 C700B driver

Will this put out more plant useable light than my 600 watt hps running a Phillips son t pia bulb??

Thats what i need to know.

To all the gurus

Thanks in advance.
Click to expand...
You'll gain a lot of satisfaction by figuring out the significance of the various parameters.

By my calculations assuming 30% efficiency (generous) for the Phillips you gain at least 20% more photons with the cxb's.

I will not show my work.
 
T

todd86

Active Member
Awesome thanks :)

Thats pretty good considering only about a 400 watt draw from the wall.

I will attempt to study this stuff once i finish work.
 
ttystikk

ttystikk

Well-Known Member
JorgeGonzales

JorgeGonzales

Well-Known Member
ttystikk said:
My 400W of CXB3590 at 50W per COB would mop the floor with that 600W HPS
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Maybe his 600W, yes. But the top shelf stuff makes 1000+ umol/s. I think the Son T stuff is not horticulture specific.

Be a fair fight against a good horticulture 600W, for a few thousand hours anyway :). I mean 50% more output is nothing to sneeze at.
 
ttystikk

ttystikk

Well-Known Member
JorgeGonzales said:
Maybe his 600W, yes. But the top shelf stuff makes 1000+ umol/s. I think the Son T stuff is not horticulture specific.

Be a fair fight against a good horticulture 600W, for a few thousand hours anyway :). I mean 50% more output is nothing to sneeze at.
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That HPS is doing very well to make 35% PARW.

My CXB3590 hits 60%. Even the corner cutters hit 50% at 50W.

HPS = 22 CRI. That's shit.
CXB3590 = 80 CRI. Yes, it matters, when the difference is THAT big.
 
testiclees

testiclees

Well-Known Member
todd86 said:
This is with the 600 Watt HPS Phillips bulb.

with 2-3 weeks veg , If its shit I'm definitely looking forward to results of the CXB3590View attachment 3736797 View attachment 3736798

(2 separate HPS grows , 2 different styles in the same tent under 600 watt HPS Phillips)

a few grams off a pound, each grow in a 10cm deep tray of hydroton, tray is only 3 x 3 or 90 x 90cm, ebb and flow, i.e flood and drain. 2 - 3 weeks veg.
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Very nice work bro. Your prob gonna have a transition period and some tinkering to master the different light engine. No doubt youll soon be killen it.
 
wietefras

wietefras

Well-Known Member
Don't forget that HPS will lose at least 19% of the light on the reflector. Plus you gave more wall losses (wider angle and higher above canopy)

All in all you can expect only 1.6umol/s/W to reach the plants even from the most efficient double ended bulbs (rated at 2.1umol/s/W)

So to replace an HPS I would go with the 1.6umol/s/W figure. Multiply that by total HPS watt (boost or not) and divide by umol/s per COB and you know how many COBs you need.

I have compared my harvest logs using HPS (Gavita 1000W pro) and now using Cree COBs. The ratio of grams per PPF is very similar. Around 0.66g per umol/s
 
wietefras

wietefras

Well-Known Member
Those measurements are pretty much useless. I really don't get the point of these "black wall" PPFD measurements. Who has black walls in their grow room really?

I have grown with Gavita 1000W and it does produce a reasonably uniform 800umol/s/m2 over a 5x5 surface.

Lets stick to actual HPS figures like 1.7umol/s/W to 1.8umol/s/W measured in an Ulbricht sphere or 1.6umol/s/W in a proper grow tent on the canopy.
 
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resinhead

resinhead

Well-Known Member
BOBBY_G said:
that explanation is confusing you can also think of it this way

calc PAR W
calc PAR W/SF
PPFD = PAR W/SF *45

thats how ive always done it. note supras numbes from this famous post

https://www.rollitup.org/t/cxb3590-1500w.878136/page-2#post-11778236

my notes are in bold italics.


@45.7%
83.63 PAR W covering 5 ft² = 749 PPFD

83.63/5 = 16.73 x 45 = 752 PPFD


@49.7%
75 PAR W covering 4ft² = 840 PPFD
75 PAR W covering 5ft² = 672 PPFD

75/4= 18.75 x 45= 844 PPFD
75/5= 15 x 45 = 675 PPFD


@ 56.3%
110.3 PAR W covering 6ft² = 824 PPFD

110.3/6 X 45 = 827 PPFD

@64%
117.8 PAR W covering 6ft² = 879 PPFD
117.8 PAR w covering 7ft² = 754 PPFD

117.8/6 x 45 = 884 PPFD
117.8/7 x 45 = 757 PPFD
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Thanks for the link to Supras famous post! It really breaks down the conversions.
 
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