All BS set aside CMH yields

I ran the 400W Phillips retrofits before they discontinued them, and then still after with the GE lamp. The only issue is the GE's are not rated for open enclosure use, so you have to put it behind glass/use fans. The 315 open bulb ends up being a lot brighter. I'm actually in the process of switching everything over to 315's because of the efficiency advantage as well as the actual light produced.

The 3100k 315w CMH is more efficient and has more and deeper reds in the spectrum.

A square wave goes directly to peak power on each cycle, where a sine wave only reaches peak power for a moment.

What is optimal distance for dual 315w cmh bulb style fixture from plant canopy. Running nanolux 630w dual single ended bulbs. Looked online for it and cant find anything including a ppfd chart

Kushandjams said:

What is optimal distance for dual 315w cmh bulb style fixture from plant canopy. Running nanolux 630w dual single ended bulbs. Looked online for it and cant find anything including a ppfd chart

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I've seen several people say "about 24 inches." I'm curious about that too.

Kushandjams said:

What is optimal distance for dual 315w cmh bulb style fixture from plant canopy. Running nanolux 630w dual single ended bulbs. Looked online for it and cant find anything including a ppfd chart

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Theres a couple of variables. I think it depends on your canopy footprint and how much light your plants can bear.
I personally keep my nanolux dual 315 cmh at 3 feet.

I’m 16-18” from canopy full bloom with dual nanos. Tops are deficient from lack of food and high ppfd but flowers below are fine. No burnt tops or bleaching

ttystikk said:

This people thinks that 315W CMH is worth about 400-450W of HPS, and about 200W of CXB3590 driven at 50W apiece to get 56% efficiency.

The trend is clearly visible from least efficient to most. Place your bets, mind the fact that you won't be able to give your old lamps away in five years. Cuz COB LED IS that much better- and by then it will also be cheaper.

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Oh have times changed

Onextremebuzz said:

Oh have times changed

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It's been 6 years and I don't see a lot of builders running HPS anymore. 315W CMH is still hanging in there but only with square wave ballasts to maximise efficiency- and even then only for those on a tight budget. The best dressed growrooms are all one variation or another on the LED theme.

I was right.