945w DE CMH vs 1000W DE HPS

Hello all!

This is my first post, although I’m a longtime lurker for years I figured I’d get some opinions on this as I haven’t found much information online yet.
I’ve been experimenting with lights and I purchased some 945w DE CMH lights to run in my veg room (and possibly flower).

I know many of you probably have experience with the 315 but, does anyone have any with the 945 DE bulb or CMH in general?
I’ve been unhappy with MH overall and have actually had better growth with HPS in veg (clones and mothers under T5) without much difference in internodal spacing, much less heat and greater PAR output. Despite that, I hear great things about CMH and a more complete spectrum may benefit the plants more. Although, there is a study that suggests more light output has more effect than spectrum and I’m sure some of you may be aware of the study.


My setup;
RDWC in a sealed room with a CO2 burner, a three ton mini split and coils with water chiller.

Who knows which is best, none should make you unhappy, hps cheaper but money shouldnt be that much a problem.

The sum of different wavelengths of light has always been more than their constituent parts but that may not equal that a wider or differing spectrum will beat the sum of hps's spectrum.

Its not really a question id expect a definitive answer from but more opinion, never has the market had so many choices but yet not one clear leader

Bought a Nanolux 1000w DE CMH.

Like the Gavita better.

jimihendrix1 said:

Bought a Nanolux 1000w DE CMH.

Like the Gavita better.

Click to expand...

Oddly enough I’m running both the Gavita and the Nanolux CMH as well! Although, just the Gavita DE bulb and not their reflector and ballast.
Could you elaborate why you prefer the Gavita?

Just seems to be more powerful, the plants like it as well, and the Gavita may cover a bit larger area, and have more intensity. I don't think the spectrum makes a whole heck of a lot of difference. I think Intensity makes more difference. They both work.

Gavita is 166,000 lumens. 1175w

Nanolux is 160,300 1275w

So the Gavita is also more efficient. Nanolux uses 100w more, and 5700 lumes less. Both are 2100umol

I've been having a bit of trouble deciding between the two myself!

I originally used to have some MH for veg and some HPS lights for flower when I used to grow in my younger days.

Now I come back and there are DE HPS and CMH, leaving me confused as to what route I should go for veg/flower.

Can anyone point me in the right direction? Do I even need 2 different types of lights or will a DE HPS work for veg and flower?

killakanna said:

I've been having a bit of trouble deciding between the two myself!

I originally used to have some MH for veg and some HPS lights for flower when I used to grow in my younger days.

Now I come back and there are DE HPS and CMH, leaving me confused as to what route I should go for veg/flower.

Can anyone point me in the right direction? Do I even need 2 different types of lights or will a DE HPS work for veg and flower?

Click to expand...

i have a lot of runs under just a 315wCMH, and now my primary light is a 630w double bulb/dual spectrum Ceramic Metal Halide, and during flower I supplement that fixture with an open bulb, vertical hanging 400w HPS (so in a 5x5 with 1030w total light) .I’ve also done a bunch of runs under HPS and/or Metal Halide only.

Ceramic Metal Halides absolutely kick ass over just HPS alone! The UVa/b in CMH bulbs will increase THC levels above HPS and/or MH. What i notice under CMH only is strong product, short nodes and stems, a bit larfy below canopy tops, and great colors...but more leaf overall. Your DE will do great on its own for quality. However, HPS makes taller plants with less leaf, thicker bigger buds overall with a slight reduction (not noticed by non growers) in potency and terpenes...but better overall for yield and “fat nugs”.Regular Metal Halide (not CMH) makes shorter, leafier but tight, crystal covered buds that are round and rock hard....but small small yields in my experience.
The BEST buds come from the sun, outdoor boutique or greenhouse! Indoor, which is what we are discussing, IMHO the absolute BEST buds come from a combination of CMH and HPS, which is why so many commercial growers use that combo, and why there are commercial fixtures that are a 1000w HPS bulb + two 315w CMH bulbs (and what made me try that combo, I love it).
Your CMH DE will make fantastic bud so go plug it in, try scrog or LST to keep canopy level. I’d recommend using the 3800Kelvin bulb with more orange all the way through veg and flower.

Geez my apologies on reading that again, your DE HPS will do fantastic on its own thru veg or flower, check out enhanced HPS bulbs for more complete spectrum...and get the biggest inline exhaust fan you can, you’ll need it with that light