Noob question about CMH Lights
- Thread starter Baked123
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cannabineer
Ursus marijanus
They run no cooler than any other HID lamp. cn
Warlock1369
Well-Known Member
Wrong spectrum.
cannabineer
Ursus marijanus
I think the spectrum is fine, but 400 watts are 400 watts, effectively all destined to be heat. cn
Warlock1369
Well-Known Member
CMH and MH use the same power. And creat the same heat. But CMH is used in flood lights. Creates better light for our eyes. But wrong spectrum for plants.
LadyMJ
Member
I have a metal halide in my vegetating area and two ceramic metal halides in my flowering room. I've found that CMH appear to be slightly cooler than the HPS, not enough to talk about, IMO. Based on specs, the CMH has a broader and more useful light spectrum for growing indoors. Basically, I agree with cannabineer.
cannabuddy42
Member
I have a Phillips 400W CMH (Open Fixture rated). This is my first time using it, and I'm using it in combination with a 600W HPS.
I ran it in my 4'x4' tent with no active cooling and no lens for the first few days of seedling life for my girls, and it was quite cool. I didn't have a 400W HPS to compare it to, but it's open fixture rated, so that says something right there. When I run the 600W and the 400W at the same time, they REALLY need to be cooled.
Watts are not a measurement of heat. Different technologies will convert electricity to light at different efficiencies. It's commonly accepted that CMH bulbs are a bit more efficient at this, with less waste (heat is energy wasted, as in not converted to light) than HPS. I am not claiming a significant difference, other than that a 400W CMH might have the advantage over 400W HPS of using a glassless hood, so less light would be lost on the lens.
Finally, the spectrum of CMH bulbs is pretty nice. It is a very wide spectrum, closer to natural light. HPS have an EXTREMELY narrow spectrum in the red zone. I'd post some graphs but they're easy to google. I am not bashing HPS at all or claiming that CMH is better. It's spending energy on light that is not exactly in the ideal spectrum for flowering plants, so HPS seems to be slightly better for that purpose. CMH seems to be much better for Veg. In combination, I'm expecting excellent results. Flowering starts in a week or so, and all 5 plants look great under both lights. And I like being able to see proper colors under the grow light
So no, CMH isn't the "wrong spectrum"!
I ran it in my 4'x4' tent with no active cooling and no lens for the first few days of seedling life for my girls, and it was quite cool. I didn't have a 400W HPS to compare it to, but it's open fixture rated, so that says something right there. When I run the 600W and the 400W at the same time, they REALLY need to be cooled.
Watts are not a measurement of heat. Different technologies will convert electricity to light at different efficiencies. It's commonly accepted that CMH bulbs are a bit more efficient at this, with less waste (heat is energy wasted, as in not converted to light) than HPS. I am not claiming a significant difference, other than that a 400W CMH might have the advantage over 400W HPS of using a glassless hood, so less light would be lost on the lens.
Finally, the spectrum of CMH bulbs is pretty nice. It is a very wide spectrum, closer to natural light. HPS have an EXTREMELY narrow spectrum in the red zone. I'd post some graphs but they're easy to google. I am not bashing HPS at all or claiming that CMH is better. It's spending energy on light that is not exactly in the ideal spectrum for flowering plants, so HPS seems to be slightly better for that purpose. CMH seems to be much better for Veg. In combination, I'm expecting excellent results. Flowering starts in a week or so, and all 5 plants look great under both lights. And I like being able to see proper colors under the grow light
So no, CMH isn't the "wrong spectrum"!