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Ceramic Metal Halide (CMH)

Sparky 6

Member
I am about to start up my closet in the next week or two and am seriously thinking of using the CMH for veg and most of flower (to avoid a lot of stretch) and using HPS for the last two weeks or so to see if it will fatten up the buds any better. But, I am open to suggestions.

Thought I read that many guys are going to HPS right away at flower then bringing in some blue light in the second half or so of flower to add trich production. I may be wrong but that's what I remember. Might have read it in this thread.
 

messn'n'gommin'

ember
Veteran
hoosierdaddy said:
I did just that run before this one, and all HPS this run.
The nearly new HPS is going back in the box for a spare and maybe for next years cold grows.

I have no controls in place, and this is just seat of my pants...the CMH seems to make things frostier, fatter, and happier all around...which makes me happy all around.
Pics are much nicer as the bonus.

Ya...that seems to be the consensus. But, in my convoluted thinking, the thought entered my head that I could use HPS (suplemented with UV) for the last two weeks of flower, to improve yield. But, thinking about it again, leads me to think it will only stretch the last stages of bud growth instead of fattening up.

stink. whistler said:
I'm not sure that's true, I looked at the pdf on the advancedtech site and it said this:
WARNING: “These lamps can cause serious skin burn and eye inflammation from short wave
ultraviolet radiation if outer envelope of the lamp is broken or punctured. Do not use where people will remain for more than a few minutes unless adequate shielding or other safety precautions are used. Certain lamps that will automatically extinguish when the outer envelope is broken or punctured are commercially available.” This lamp complies with FDA radiation performance
standard 21 CFR subchapter J. (USA:21CFR 1040.30 Canada: SOR/ DORS/80-381)
.


From that standard:
(4)Outer envelope means the lamp element, usually glass, surrounding a high-pressure arc discharge tube, that, when intact, attenuates the emission of shortwave ultraviolet radiation.
Maybe there is another reason than UV for the frostyness? Or maybe just the bits that do get through are enough? It also may just be generic verbiage they put on all their lamps, since it seems it may also refer to non open rated lamps.

The warning is required by the effdeeay on any MH lamp sold in the US and technically the CMH is a MH lamp. Still, I think the operative word here is...attenuated. Although, the materials and/or coatings used, might reduce the incidence of UV light, it is going to be considerably less than it potential output.

However, and something to consider, I have a report somewhere that mentions, almost in passing, that less than 1 mmol/m2/s of UV is enough to trigger a plants defense response.

Sparky 6 said:
Thought I read that many guys are going to HPS right away at flower then bringing in some blue light in the second half or so of flower to add trich production. I may be wrong but that's what I remember. Might have read it in this thread.

lol...That is just the way my brain works. I figured that if HPS was better at quantity and CMH was better at quality, I could go counter to conventional wisdom and add a bit of size to quality buds. Rather than a bit of quality to quantity of bud. I may still do it to see what's what (but, add some UV and eliminate EOD treatment), but, i have time to think about it until then.

whatissixbynine said:
ok lets see how long it takes till i can officially be in the CMH club for reals \o/

I've got about 4500 hours on mine so far. Three or four more grows and I should be about due for new.
 

Sparky 6

Member
lol...That is just the way my brain works. I figured that if HPS was better at quantity and CMH was better at quality, I could go counter to conventional wisdom and add a bit of size to quality buds. Rather than a bit of quality to quantity of bud. I may still do it to see what's what (but, add some UV and eliminate EOD treatment), but, i have time to think about it until then.

Oh absolutely- no one has all this figured out. I don't mean to inhibit your experiments at all- the more you all experiment and post the results the bigger database we all have to work with. :)
 

treewizard

Member
While the higher watt lights are better at converting raw power into usable light, you can still get better light coverage from multiple light sources. I saw a post where a guy was running 4 cmh and the plants under it were huge and didn't seem to be left wanting. Plus I'll bet that 1,200 watts of cmh would still throw less heat than a single 1000 watt hps.
 
W

w.wonka

had some probs with my 400 and had to return it and told the lady that i would get back to her on what new ballest i wanted to pick up.. saw they had a power house 430 and was thinking about it but was leaning more too the switchable 400... then she said if i got the 430 that i could use the cmh 400 in the 430 ballest without a prob.. i know u can use 430 bulbs in a 400 but what she said true.. could i use the cmh 400 in that 430?? w.wonka
 
W

w.wonka

anyone with any knowledge purtaining too using a 400 bulb in a 430 ballest?? w.wonka
 
While the higher watt lights are better at converting raw power into usable light, you can still get better light coverage from multiple light sources. I saw a post where a guy was running 4 cmh and the plants under it were huge and didn't seem to be left wanting. Plus I'll bet that 1,200 watts of cmh would still throw less heat than a single 1000 watt hps.

I highly doubt 3 - 400W CMH would put out less heat than one 1000W. I've owned several 400W's and 1000W's and there isn't nearly as big of a difference in heat as people make it out to be. Sure, the 1000W gets damn hot but the 400W's aren't exactly cool. They still are very hot themselves. One other reason i prefer the 1000W is because of light penetration and the pure light strength. My main colas are usually 11-13 Inches tall and 6-7 Inches thick, and even my lower budsites are nice, it will penetrate several feet into the canopy. I never got colas like that when i used 2 - 400W HPS.
 

Sparky 6

Member
I think he's speaking on the lower level heat produced by the CMH when compared to HPS rather than multiple light sources being less hot than one large one.
 

elMarcel

New member
Hello everybody, and hello Simba if you are still here :)

I use CMH 400W since 2007, and I love this bulb.

On the last run I tried to flower under HPS 600W to boost the yield, because there is not any CMH 600W.

And I had a very bad suprise : when I switched the bulb from CMH to HPS, around 3/4 weeks of 12/12 (at the end of the stretch), all my plants became hermies ! :puppydoge

Of course I always use regular seeds from serious breeders, or well known clones like UK Cheese (Exodus cut), so the genetics are not the problem.

A friend explains me the exact problem :

When I switched from CMH to HPS, the amount of UV decreased very much. The plants use UV rays to estimate the power of the sunlight, so when the amount of UV decrease a lot, they think winter is already there, so they turn hermies to maximise chances of pollinisation.

In fact this changment of light caused an important abiotic stress, and a forced reproduction !

This problem does not happen when you swith from MH to HPS, because there are vey low UV, both in MH and HPS, and their spectrums are different but very poor.

So I have two solutions :

- to do all the cycle under CMH 400W, like on my previous runs, but the yield was not enough for me

- to do the grow cycle and stretch cycle under CMH 400W, then to switch to HPS 600W, BUT with adding 2 or more neon lights to improve the spectrum.

I hesitate between these neons lights, so I ask you, what do you think is the best between :

* néon "Purple" (25 000K), like this one (55W, T5HO) :
PURple™ ? YES. Introducing the Nlite™ PURple™

PUR stands for Photosynthetically Useful Radiation.

Humans are most sensitive to green light (green curve below). Wide spectrum light with lots of green appears to us as white.
Plants use a part of the sun's spectral range to grow. This is known as the PLANT ACTION SPECTRUM. (yellow curve)

Plants look green because they reflect most green light, and absorb most red and blue.
Plants therefore respond more to light from the RED and BLUE ends of the plant action spectrum.
PURple™ lamps have this ideal spectrum shaped the way plants "see" the light. (white curve) ( a little spike of green is left to allow US to see plants lit by PURple)

a1dd5.jpg


Nlite™ lamps are made in 3 PUR colours. Plants change their growth response to different levels of these PUR colours :-

PURple (25000K) - The Ultimate 100% PUR. Purple is perfect for all stages of plant growth, germination, root development, tuber and bulb formation and gives lots of internodal growth, and budsites. Great for orchids, cacti, ethnobotanicals, coral, sea plants etc. A small amount of NEAR UV ensures good production of essential oils - Great for Basil and other aromatic herbs.
or :

* néon for reptiles, very rich in UV, like Reptisun or Arcadia 12% (12% UV(B) and 30% UV(A)), like this one (T8, 30/36W) :

Arcadia D3 Reptile Light 12% Tubes are designed to ensure your reptile receives the UVB & UVA rays he needs for vitamin D3 synthesis and ultimately help avoid health problems such as metabolic bone disease. They are suitable for desert type set ups as they provide high level UVB rays equivalent to those experienced in cloudless desert environments.
The Arcadia tubes provide full spectrum lighting, meaning they simulate sunlight and will enhance your reptiles colourful appearance.
The Arcadia 12% D3 bulb will produce significant UVB rays at up to 20" away from your reptile. The light should be on for around 10 - 12 hours per day.
Arcadia UV tubes should be replaced around every 8 months to ensure optimum UVB levels are maintained.



d3reptilespd2.gif


What is the best choice to add to HPS 600W, according to you ?? Purple bulb or reptile bulb ?!

Thank you very much !!

Marcel

ps : I have a lot of pics under CMH 400W, I will add them to this thread soon !
 

MrBomDiggitty

Active member
Veteran
Are you sure you didn't get a bunch of hermie plants because of the change in heat stress from the 600w vs. the 400w?

I switch from my 400w CMH to my 400w HPS all the time and not a single hermaphrodite
 

GrnMtnGrwr

Active member
Veteran
Yeah I'd like to get some more info about that... I was planning on switching from CMH to HPS a few weeks into flower... this is the first I've ever heard of it causing hermies.
 

elMarcel

New member
Last year I gave a CMH 400W bulb to a good friend, he switched to HPS 400W after 4 weeks of 12/12, and all his plants turned hermies, too. At this time I did not understand the cause was the difference of spectrum and UV amount.

And now I tried switching and I had exactly the same problem !

> MrBomDiggitty > When do you switch from CMH to HPS exactly ? have you tried on numerous strains ? because not 100% of the plants turned herm, but the majority was....

In fact, switching from CMH to HPS, is the same as switching from the outdoor sun to indoor HPS.... very important abiotic stress for the plant.
 
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