In theory, CMH > HPS?

So, take a look at the light spectrum for Ceramic Metal Halide bubls.

Phlips MasterColor Ceramic Metal Halide ~ CMH ~ HPS-Retro White

So by using a 400watt CMH during veg and during flowering, that should result in a better overall Plant than a 400watt MH during veg and 400watt HPS during flower.

Any opinions? You will win yourself a big highfive and a joint smoked in your glory.

anyone? sorry to spam like a noob, but i cant find anything in search about cmh bulbs

I dont know but i am wondering the same thing because im about to get a eb and want to know whether or not to just keep my metallic and get a cmh. I would rahter get the eb and switch from metal to hps but if the cmh is better then i want to stick to that. Someone out there has done it im sure.

Blue light has the effect of supressing a class of plant hormones called auxins. Auxins are very important for the flowering process so any light kicking lots of blue light should be avoided for flowering. The CMH kicks out lots of blue light so would be more appropriate for the veg stage since we want some auxins supression so that the plant does not get all elongated.

This particular light has been optimized for human vision and not plant growth. Remember this point!

THANK YOU you just made up my mind. you are absolutly right it was made so it would give a whiter light for warehouses so it wasnt so yellow. which has nothing to do with plant life. Im going to stick to what works and get an eb that can do mh and hps so i can switch from veg to flowering. It sounds like that is the way to go. Thanks man

I use a 400w CMH for veg and it works great. The plant is compact and very healthy. I use regular HPS for flowering.

googlesworth said:

So, take a look at the light spectrum for Ceramic Metal Halide bubls.

Phlips MasterColor Ceramic Metal Halide ~ CMH ~ HPS-Retro White

So by using a 400watt CMH during veg and during flowering, that should result in a better overall Plant than a 400watt MH during veg and 400watt HPS during flower.

Any opinions? You will win yourself a big highfive and a joint smoked in your glory.

Click to expand...

no.......but thanks for playing..mh does a great job in veg but shity in flower....hps on the other hand will veg a plant well and kick ass during flower....hps is the best light you can get today period.....if you are looking to get only 1 lighting system for your grow hps all the way..accept no substitutes,,,,

nickfury510 said:

mh does a great job in veg but shity in flower....hps on the other hand will veg a plant well and kick ass during flower....hps is the best light you can get today period.....if you are looking to get only 1 lighting system for your grow hps all the way..accept no substitutes,,,,

Click to expand...

false. hps produces more lumens per watt, so on a watt for watt basis they are slightly more powerful. they have a very unnatural light spectrum but for growing bud and other flowering/fruiting plants it works great.

hps gives bigger yields per watt PERIOD.

this does not make it the best light all around, MH produces UVB light which will enhance trichome/resin production and will keep nodes short creating a flatter canopy which gives a more even bud distribution and gives you moremedium-large buds insteaad of a few massive cola buds and a sackful of popcorn fluff nugs.


and to whomever mentioned auxins as a flowering hormone is somewhat incorrect, auxins are a class of hormones that direct all types of plant growth... this is a gross generalization and is just plain incorrect.


the short version.

flowering with metal halides will give you a better looking more compact plant with dense nugs and a higher thc content. however with two identically rated lamps a metal halide will yield ~15% less than the hps.

so if you're a commercial grower who needs that extra 15% to make cash go hps, or if you just want the biggest buds possible, go hps.

if yield is less important but quality and consistency is, go metal halide.

the new 7200k mh's are sick, and it just makes those trichomes glint like diamonds!

But he's not talking about standard halides, he's talking about ceramic metal halide.

Actually a CMH would work better all around than a HPS except for the fact that they are designed as conversion bulbs to run in HPS ballasts and throw less lumens than the hps bulb would by quite a bit. (these don't work in halide ballasts, only hps ballasts and I think they require magnetic too but not sure on that last part)

What you want to run is a pulse start halide. It has the full spectrum same as CMH without the losses of a conversion design. They require a pulse start halide ballast though, so you're locked in. Here is a cheap one, click this link twice to get the right page:
http://www.e-conolight.com/Product/EProductDetail.asp?ProductFamilyID=8&FGNumber=E-HB5P40Q

Sure it may cost more having to buy a new ballast but the bulbs are so much cheaper than CMH bulbs that it would pay for itself with just the cost of two bulbs.

I don't know omeds. I am just finishng a run under psmh and I'm dissappointed so far. I don't think resin development exceeds my last hps crop even though these are healthier plants overall. There is much leaf and the buds are tiny comparitively. Even though it is designed to be used with the connected ballast, the lux output is sad. In a PL deep reflector, the 600 psmh is 70% as intense as a 400 w solarmax in a cheap gullwing reflector. Switch reflectors out and the mh goes to 55% as intense. This is measured over a 36" grid and suprised the crap out of me. This was a 3k psmh. I won't be using it again. Sample pieces tasted no better than last crop. And there's gonna be twice as much trimming too. Ugh.

Which ballast/light do you have? I'd like to look it up. I believe you, sor far I haven't tried it but in theory if you have a psmh bulb that throws the same or similar number of lumens it should be superior.

I have the 3k Sunpulse, 600w psmh. I run it on a galaxy. Since my hydroshop owner loves me I was able to test it for a week each using the Digimax and the Solar-E recommended by Lifelite. The Digimax was about 5% brighter than either other ballast. But it's cost makes a 5% gain negligble. The Solar-E looked to the eye to be bluer as well. Both ballasts I borrowed were plugged into a 16' length of 10 guage cable plugged into my dryer receptacle. The galaxy uses a 16' 120vac dedicated line. The meter used was a hydrofarm digital footcandle meter. The amazing thing was the intensity dropoff at equal distances between the bulbs. At two feet, the 400 hps was 20% greater. Lower buds on this crop are sad. A good 7" budset may weigh 2 g once dry. In comparison, I had 3" eigths last time. They were rock hard and with this crop, you can see light if you look sideways through a bud. On most of this crop I used coco, though I am running two soil plants grown in the same mix as last crop and topped and trained the same. I also have very weak stems this run. I will say though, I needed to scrape the scissors more often when trimming the samples I took. These were at 63 days of a 70 day cycle. However, I also needed to chop through stacks of leaves with these buds so that may have accounted for some of it. I'll know for sure in two weeks but my experience tells me these bulbs are more hyperbole than anything else. I'm 99% sure I'm using hps next time even though this bulb wasn't cheap.

Based on the info, the lights have a 4000K rating, hence, not great at either veg or flower.

so what was the verdict on the 3k psmh dragon?

then just use a HPS through out. then add a 15 dollar reptile lamp to give UVB for trich production and resin abundance

Here are my results using 400w ceramic metal halide throughout.

g13 Gigabud


Blue Moonshine


Any more questions?

got mine under a chm now 400w and they are very healthy bushes, cant wait to see some buds though. Im switching to 12/12 in a week, they are 1 month old and already have pistals everywhere!

How's that grow going Macriv? Pics?

Beautiful buds GreenCross, did you notice a higher or lower leaf/calyx ratio under the CMH bulb?

the cmh forum at ICM say's not to use pulse start bulbs only the philips retro whites with an magnetic ballistic I am going to try one out. Yield is not as importaint as quality for me.

Lots of misinformation in this post. A CMH puts out MORE RED than an HPS, and MORE BLUE than an HPS.

An HPS bulb looks "red" but most of the light is in a yellow/orange spectrum that plants don't use. A CMH doesn't look red because it has a lot of blue.. blue is good during veg and flower.

CMH also puts out less heat than an HPS. The color spectrum of a CMH is very impressive (see below), but there are 2 major downsides. First, CMH is only up to 400w right now.

And it only works with a magnetic ballast. Magnetic ballasts give off more heat than digital ones, and they only run one specific bulb. i.e., a metal halide magnetic ballast will only light a MH bulb. A CMH runs on an HPS ballast.



btw DO NOT use advancedtechlighting.com - the guy is lazy, and his "business" is a ripoff. He doesn't respond to mail, and sent me the wrong order. Refuses to acknowledge this, let alone fix it. I have since bought the parts I need locally. This site is by far the worst e-commerce site I've ever used.