Please Help me pick a CMH Light

I’ve got the go-ahead from my wife, and just got the right seeds (they sent me the wrong order and now I have extra :).

I have a 4x4 tent for my space. Ideally I want to grow 4 plants. I’m pretty sold on CMH/LEC lights. My local hydrostore recommends Sun Systems LEC 630W which is $675. It includes one 3.1k lamp, so I think I would have to buy the 4.2 for growth stage (or ■■■■ versa?)

Someone else recommended Hydro Crunch 630W for $375. This is a double ended bulb instead. But again I have to get the 4.2k on top.

How do I compare these other than cost? I’d be happy to pay a lot more for higher quality/safety/performance but I don’t want to waste money. I’m not married to these lights but I’m leaning towards the SunSystems because the company seems pretty legit and the ballest is in the lamp.

Are either of these lights good for a 4x4 tent for both stages? Should I consider something better?

So excited to start :):grin:

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I believe @HornHead uses CMH and i know @dbrn32 and @Aolelon both know their lighting.

The 3100K is good enough to do veg stage AND flowering stage.
The 4200K is better for strictly vegging.

Pretty sure that SunSystem would do exactly what you want and better

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I would recommend the Phantom 315 by Hydrofarm. The ballast is separate from the hood, so can hook up ballast away from grow area keeping it cooler. I have it in 3100k Phillips bulb and its a really nice light. I also have a Sunburst 315 wit ballast attached in 3100k Phillips bulb, also a great light i would recommend, i also have a SolisTek 315 C1 series with 4200k veg SolisTek Bulb,with their 3200k flower bulb on standby Also another great light.
I would also recommend getting 2 315s instead of 1 630 so you can spread your light out more evenly

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No likes to give but thanks. Ur now in my ‘lighting rolodex’ under cmh :joy::joy:

3100k should be plenty good for seed to harvest growing. I would definitely try a run under it before spending extra on the 4100k

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6500 Kelvin for veg… 3500 Kelvin for flowering… please look into the hobby your looking at…
Lots of info out there … even here… :wink:
Ruff day for me… tired of seeing same posts… not your fault… but there is plenty of info right here…
Sorry if I’m too blunt…

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You really only need to go with a color temp that cold if you have extremely low light levels, like cfls. With cmh or some high intensity leds, 3000k plenty good.

@MattyBear has a whole tent full of plants started under 100 watts of 3000k leds. Maybe he can drop a few pics.


We need some sort of basic information and a place to send them to… I dont have alot of time to share … which sucks for all of us … just like you @dbrn32 … so much info but to many new threads… we need to figure this out… :grin:
I’m still a jerk , either way…:grin:


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I agree. I’ve typed same response several times, I’m sure a few minutes with search bar would provide ample feedback. I just figured in the same time I could type look for it, or drop a link, I could answer again is all.


I love to share… I just dont have much time…
I think there needs to be a door for people that need basic info … before they get to ask us…
I know that’s harsh , but I’ve only been here to get seeds… I feel bad and need to share… not a greedy person… just dont have alot of time…

Not the thread for this info…
Hit me up… :grin:

@dbrn32 not as easy as we think… much luv my friend… :heart::heart::heart::heart::heart::heart: this for all your info… :grin:
All I got… :wink:


This is identical to the set up I’m using and I have it on a light mover. And I absolutely love i use the 3100k veg and flower it Grow Co. 630W Ceramic Metal Halide CMH System w/Philips 3100K Full Spectrum Bulb 240V Power Cord


Advanced Platinum Series P450 450w 12-band LED Grow Light - DUAL…

Thanks. My concern was that 2-315’s would not fit as well in a 4x4 tent, especially if I wanted them air cooled. Would they fit? I’m actually going to build a shed and want to have 2-615’s eventually for 6 plants.


Cmh lights are generally not air cooled. But the Phantom 315 has the ability to be cooled with additional parts. With the right intake and exhaust setup they do not need it. If the room where the tent is gonna be is already cool it should not be too hot. As for 2 fitting, it might be a tight fit depending on which model lights you get. I think 2 Phantoms would fit perfect. I will get you some measurements in a few hours once my lights turn on.


I’m going to bring this back up because it was never addressed and I am wondering about this as well…
Will (2) 315s fit and cool well in a 4x4 tent?
Is a single 630 a better choice for this scenario? (Considering light output, heat output, space used and cost)

EDIT: Doh. I didn’t scroll down far enough to see Dr.DankThumb420’s reply. I’m still inclined to consider a single 630 though just for cost reasons.

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You’re basically considering a single point source vs 2 point source. I haven’t seen anything suggesting either is a more efficient source, both come in around 1.7-1.9 umol/joule. Stretching a 315’s footprint out to 4’ will be tough regardless, it’s really an ideal setup for a 3x3. The ppf is high enough to do pretty good either way. The amount of heat within your grow will depend a lot on your intake air temp and ability to move it through your space. Some people struggle keeping a 600 watt light cool while others can do 1000 watt no problem.

I think to make either situation ideal it’s a mattter of throwing two 315’s on a mover, or being able to get 630 high enough over canopy to have decent footprint. This is why cobs, strips, and qb’s have become so popular. Having multiple point sources allows you not have to worry about that height vs footprint as much, and they are just as or in most cases more efficient than the cmh. You simply have to give up the uv and spend a little more to get into them.

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So I ended up getting two 315s. The salesman strongly recommended it over 1 630 because of how it would broadcast the light better. Honestly, 2 fit fine in my 4x4 tent. A little cramped, but its fine.


Nice. Your gonna like the 2 315s over the 1 630.

Advanced Platinum Series P450 450w 12-band LED Grow Light - DUAL VEG/FLOWER FULL SPECTRUM

I’m ordering this for me and if hung @ 18" off the floor it covers a 4’ x 4.5’ area

I’m sorry I didn’t see this sooner I hope you didn’t order that light. It’s way over priced and won’t even cover half the space you need it to. I’m sure we could find you alternatives that are legit lights instead of lies.

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