315 \ 630 Watt CMH GRAM PER WATT compared to LED and HPS?

So they say

HPS can produce 1g per watt
LED can produce up to 3g per watt

I've never heard about grams per watt while speaking on CMH ... Does anybody know ? I've only heard that 315w is almost equivalent to a 1000w HPS with better penetration.. so it that's the case then would it be close to 2-3 grams per watt ?

Tried all 3. Only done one run of CMH was a 630w DE setup.

Don’t know about a 315w having more light penetration than a 1000w…

LED produced the most dense buds and compact plants. In fact was 50% more yield than my HPS. Was a Gavita 1700e pro so decent light.

CMH seemed to make the plants look happier (praying leaves etc) and produced nice buds but LED is king for yield in my experience

My favorite is CMH with LED. Best of both worlds.

Watts are watts, not magic.

I grow with a 630DE CMH and i agree with Pada.

All lights have pros and cons. Environment and working under should also be considered.

CMH is my favorite light, but LED is the king of yields, and the quality is comparable. I live in a rural area with fairly frequent power outages, and when the power starts flickering on and off rapidly you want to have an LED and not an HID plugged in. Hearing that thing try to turn itself on over and over again, but be denied by the hot restart system is unnerving-it sounds like aliens are invading. Plus, if you ever had an HPS bulb explode inside a tent before, well, it's scary. LED just feels like a safer option-otherwise, I would do CMH during winter and LED for the rest of the year.

315 CMH and a poor mans LED in the 1.2

I’m planning on swapping out the 2 x 1000w HPS in the flower room for 2 x 630 CMH’s sometime in the future.

GreenestBasterd said:

315 CMH and a poor mans LED in the 1.2

I’m planning on swapping out the 2 x 1000w HPS in the flower room for 2 x 630 CMH’s sometime in the future.
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Just watch the DE CMh lights have a hot/light spot in the middle which caught me off guard

I don't know who's telling you a 315cmh can equal a 1000w hps but they are delusional.
Now a 630 de might equal a single ended cheap hps with cheapest bulb but that's a might!

Just forget about gpw and concentrate on filling your space to best suit your lighting.

I could tell you a one sided tale of how I switched from 3x 600w hps to about 1200w of quality led and how my yield went way up, because its true.
But I also made far more effort training them plants, cut my numbers down, increased my veg by two weeks and changed to fabric pots all around the same period. Not a fair comparison.

I like a 315 cm in veg, but I prefer a 400mh for plant structure.
Now I've only tried flowering once under 315 and it was in 3x3 ft, I didn't think it really cut the mustard.
Looked nice but didn't have the density or Size as a 320w led set up had under the same conditions.

I love LED for flowering, I really do, but in winter I need to pump my veg tent into my flower tent to take the chill off without adding heaters.

Don't listen to any manufacturers who sell lights by telling you a gpw , because they are demonstrating how untrustworthy they are!

coreywebster said:

I don't know who's telling you a 315cmh can equal a 1000w hps but they are delusional.
Now a 630 de might equal a single ended cheap hps with cheapest bulb but that's a might!

Just forget about gpw and concentrate on filling your space to best suit your lighting.

I could tell you a one sided tale of how I switched from 3x 600w hps to about 1200w of quality led and how my yield went way up, because its true.
But I also made far more effort training them plants, cut my numbers down, increased my veg by two weeks and changed to fabric pots all around the same period. Not a fair comparison.

I like a 315 cm in veg, but I prefer a 400mh for plant structure.
Now I've only tried flowering once under 315 and it was in 3x3 ft, I didn't think it really cut the mustard.
Looked nice but didn't have the density or Size as a 320w led set up had under the same conditions.

I love LED for flowering, I really do, but in winter I need to pump my veg tent into my flower tent to take the chill off without adding heaters.

Don't listen to any manufacturers who sell lights by telling you a gpw , because they are demonstrating how untrustworthy they are!

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I find bulbs make a huge diff. I only run ushio and sunmaster full nova to flower in my cmhs

I veg under LED and flower w/630w LEC CMH. It has double 315w phillips 3100k bulbs. In a 4x4 flood table w/chelated nutes I clear 1000g, when everything is perfect I'll get 2g per watt but it is w/ my dialed in gg4 hybrid.

I've been growing with LED's since 2015. Along the way I've tried Cmh and SHPS too. My first LEDs were California Light Works Solar Storm 440's, the 550's and their cobs too. Okay results, but always lacking density, frost was okay and yield average. On to cmh, good quality and yield when using two 315's with Phillips 3100k bulbs.
Shps with 600 watt, 2k hortilux bulb. Better buds and yields. However, heat management (non-tent) 12x12 area required fan for bulb cooling. Didn't care for that. Switched to Timber cobs. Now have a Fatty VS with 900 watts and 1750k, 3k and 4k cobs. Averages out to a 2525 color spectrum with a HPS profile. I've added two Solar cure uva/b fixtures to that as well. That light is a beast. Excellent quality and yield. During cooler weather I run that with a 4 bucket RDWC system. I run Mephisto or Fastbuds autos under it and average about 8oz per plant in about 12 weeks.
All that being said, I'm starting two photos and plan to run them under two 315 cmh's 3100k.
These will be done in ProMix hp with light nutrients and microbes.
I'm delving into quantum boards with the Timber Magnolia. I plan on trying some autos with that and the RDWC set-up.
My story is one of lots of experimentation. In summary, early LED's I'd rank last. Hps and Cmh are about a tie. The Timber Fatty Cob with the uv supplement is the most consistent. It produces weight and quality and is easy to work with. (See buildasoil results using timbers on you tube). I'm still experimenting with the Magnolia. I have one grow under it that produced decent results. However, next time I plan to use better genetics and stick with Promix hp for non hydro grows.
So, as we all know it's more than just light. However, my experience with older LED technology kept me searching for alternatives. Granted, I was also gaining more experience as a grower. So, I can't just attribute better results to better lights. It's all tied together.

Knch63 said:

You're right, "grams per watt" (g/W) is a common metric used to compare the efficiency of grow lights in converting energy into plant yield. While it's true for HPS and LED lights, the information about CMH being equivalent to 2-3g/W needs clarification.

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I weighed my last batch (usually don’t) and got 34oz out of a 4x4 with 6 autos using the 630w cmh. It was only running at 510w too.

Great bud density and really helps in cold conditions.

I think with the right photoperiod strain 3gpw is achievable

The lights only half the battle you can have the best light in the game and still yield shit or pull good yields its down to you your skills and genetics imo plays a part too as for what lights best well it really depends on your situation for me hps still does the job i have thought of switching or blending led with hps but im still undecided i know if i go all led i gonna need to add heat hence why i never bothered so far

conor c said:

The lights only half the battle you can have the best light in the game and still yield shit or pull good yields its down to you your skills and genetics imo plays a part too as for what lights best well it really depends on your situation for me hps still does the job i have thought of switching or blending led with hps but im still undecided i know if i go all led i gonna need to add heat hence why i never bothered so far

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I’ve been toying with the idea of adding a few LED strip lights to cover the tent better either side of the cmh. May work for your situation?

Nutty sKunK said:

I’ve been toying with the idea of adding a few LED strip lights to cover the tent better either side of the cmh. May work for your situation?

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Aye i was thinking like one of the bar style ones so along same lines as strip ones i think ?

conor c said:

Aye i was thinking like one of the bar style ones so along same lines as strip ones i think ?

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Aye that’s the one! Help get some light into the edges of the tent

As someone only moved over from hps to led its hard enough like changing your whole style I think

Philips know their shit