Hps or cmh vs LED.

543
143
Hey guys, I recently just finished up my first LED grow, and was very impressed by the results. Rather amazing really considering the LED only draws 250w.

So I was thinking of getting another tent and running cmh or hps to compare the two. I want to give the LED a good challenge, so my choices are a 250w HPS setup or a 315 cmh setup.

I feel the cmh might be a bit unfair since it's almost %30 more wattage. But I figure I could do the math and subtract that % from the result. But I like the idea of hps since it's the same wattage, cheaper, and easier to get.

Any ideas? What would you choose to run up against a 5 cob 250w LED?
 
Hey guys, I recently just finished up my first LED grow, and was very impressed by the results. Rather amazing really considering the LED only draws 250w.

So I was thinking of getting another tent and running cmh or hps to compare the two. I want to give the LED a good challenge, so my choices are a 250w HPS setup or a 315 cmh setup.

I feel the cmh might be a bit unfair since it's almost %30 more wattage. But I figure I could do the math and subtract that % from the result. But I like the idea of hps since it's the same wattage, cheaper, and easier to get.

Any ideas? What would you choose to run up against a 5 cob 250w LED?
Try a bigger tent and run 3xLED against 2X 315... that would be interesting. :)
 
1,646
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Try and match up recommended footprints rather than wattage. HID are less efficient, that's not even debatable. Running a 250 HID vs 250 LED would be silly, LED will win.

for a 4x4 your competition would be a 315 CMH or a 400w HPS in my mind.

I'd like to see a side by side with the 315 personally.
 
908
93
I feel the cmh might be a bit unfair since it's almost %30 more wattage.
But, we always hear LED is that much more efficient. (It's not clear to me because so many people run LED at 60w/sq ft.). It seems like 250w LED (27.8w/sq ft) versus 315w (not counting the ballast) CMH (~38w/sq ft, counting the ballast) would be reasonable and fair? In 3x3' tents would be best. But, 4x4 would work. I wouldn't expect either fixture to do much at that outer edge.
 
543
143
Try and match up recommended footprints rather than wattage. HID are less efficient, that's not even debatable. Running a 250 HID vs 250 LED would be silly, LED will win.

for a 4x4 your competition would be a 315 CMH or a 400w HPS in my mind.

I'd like to see a side by side with the 315 personally.
This seems to be the general consensus. The CMH is actually close in specifications. They are the most efficient hid, so would probably make the best comparison.
 
LEDs vary widely in efficiency, there's a few YouTube channels doing ppfd tests on lights these days. According to MIGROs tests here are some efficiency ratings in ppfd/watt (just a few of those tested):

Viparspectra v300 - .98
600w HPS - 1.2
CMH - 1.29
Mars reflector - 1.3
Double ended 1000w hps - 1.39
Mars sp250 - 1.8
Hlg qb96 - 1.98
Optic 1 - 2.04
Fluence Spydrx - 2.17
Hlg qb288 v2 - 2.21
 

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