What's new
  • ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here. Prizes are seeds & forum premium access. Come join in!

Ceramic Metal Halide (CMH)

Murphy

Member
MPL said:
I'm not saying you are wrong, but take a look at Murphy's 400w CMH grow. It is quite impressive, and I don't think anyone would say that his buds are not dense and dank.

Thanks for the props MPL.
Simba, thanks for all of your guidance.
I couldn't keep a 400 watt HPS bulb cool in my cab without an air cooled hood, I thought about dropping back to a 250, then I cought onto this thread and with some creative work....


Say whatever you want about CMH but, if you haven't at least tried it.....you don't really have anything to go off of.



as for dense, you tell us.


By the way, I'm a novice, 2nd grow, first harvest.
 

MPL

Member
God Murphy those nugs are so dankified it makes me all hot and bothered. I have so got to get some Grape Krush beans. You wouldn't be a legal medical user in CA with some clones would you? :D
 

OsWiZzLe

Active member
I've tried CMH I own (4) 400 watt Ballast each with CMH bulbs....that being said..that herb looks dank for sure...i bet u would have gotten twice the yield on an HPS bulb...once those nugz dry up and lose all that water.....wont be much to write home about...still though...its bomb bizzzel herb
 

Murphy

Member
OsWiZzLe said:
I've tried CMH I own (4) 400 watt Ballast each with CMH bulbs....that being said..that herb looks dank for sure...i bet u would have gotten twice the yield on an HPS bulb...once those nugz dry up and lose all that water.....wont be much to write home about...still though...its bomb bizzzel herb

I'll post dry weight after I chop. Grape Krush may not be the best to go off of anyway, not many others to compare to and everybody has different phenoms. Next up for me is AK-47, we'll be able to tell more with that! Also I have some Mandala Safafi Mix in the cab but, they are in dirt...... believe it or not, I only know hydro, never did anything in soil before and I can't keep house plants alive. If they make it, I'll be surprised.
 

MPL

Member
What bulb would you recommend then?

OsWiZzLe said:
I've tried CMH I own (4) 400 watt Ballast each with CMH bulbs....that being said..that herb looks dank for sure...i bet u would have gotten twice the yield on an HPS bulb...once those nugz dry up and lose all that water.....wont be much to write home about...still though...its bomb bizzzel herb
 
Last edited:

simba

Sleeping Dragon
littlebigman, my thinking that in his case its going straight up is im sure it tried going either cmh side but realized it would get equal coverage dead center.. IE if when it tried one side or another it relized the other side would loose energy..

well see when he moves them to the sides..

that was one of our problems with cmh and hps far away you would get plants going to the blue.. thats nature not bad.. it thinks the blue is where the real sun is.. (i think)
(i had a tomato Bush with actinics on one side and its all sprawly there.. the plant spent the time to bush up there<<< Ill find the pic)

id recommend a standard HPS bulb.. and just replace it twice as often.. pick up 2 for 40 vs 1 horti hps at 60 min and you still should replace it at half life.. abouts.. *(in euro they re lamp Legit Commercial greenhouses every few months like 2-4)

You will notice the horti Hps are higher lumen than standard hps but if u look at there spd they do it by increasing Yellow range (where the plant CANT use it well like 5% of itish..)
there are few hps with higher than standard lumen without increasing yellow so much and gets it in the red more.. (i dont know brands off at the moment.. ill look around my papers, cant think if there avail any more)
 
Last edited:
what's the verdict on CMH vs. HPS for flowering?

I'm currently vegging under a 400 watt CMH, and am planning on adding a 2nd, but I've seen more than a few folks here and there claim that the yield wasn't what they were getting with a HPS.

So what should I run for flowering? 1 CMH and 1 HPS (if HPS, what bulb would be best?), 2 CMH, or 2 HPS?

For veg, should I run 2 CMH? 1 CMH and 1 HPS?

What do you all think?
 

afghanica

Member
I have a Sunleaves Pulsar Two-Way Mini 250 Watt. It does MH and HPS with the flip of a switch. I was told the HPS is ANSI S50.
Does anyone know if it'll run CMH?
 

MPL

Member
It'll run a 250w CMH just fine.

afghanica said:
I have a Sunleaves Pulsar Two-Way Mini 250 Watt. It does MH and HPS with the flip of a switch. I was told the HPS is ANSI S50.
Does anyone know if it'll run CMH?
 

simba

Sleeping Dragon
1love.. those people.. unfort none of them have any documentation.. (sideby side vs the many supporting)
id go 2 cmh's if the area supports it..
remember you dont need overkill the plant is getting full spd which means more food from light and more energy etc to proses nutes to usable food and use it..
if ur going to add hps no mater what get a basic 400 hps from comercial supply house.. IE LU400

side note if youll notice the plant pictures being nocked mainly are ones by NEWBIES>> and its expected there first few runs to be iffy..
also when i first switched to cmh there was a bit of a simple learning curve.. IE shorter veg, silica needed, bit higher ppm..(within reason, plant gets hungrier off cmh,,)
i would say the newbies will master cmh or any grow style faster than a experienced grower as they have a hard time forgetting what they know to be fact under "old thoughts"
i have to admit i was one of those stubborn at first cause lumen etc hype about horti bulbs etc.. but now im passed the point of die hard supporter

as far as penetration.. hps ya has more lumens so technicly it has more Pen. however you have to have it higher than CMH>cause it will COOK your tops.. . so you loose Mass there (inv sqr law light Loose 4 times per equal distance)
and if you will notice under hps most are tall as can be.. under cmh with short veg (long veg not needed to mature plant full spd does that)
so you dont have to pen as much any ways..
so when u combine those two cmh has more enegy at plant level..(FULL SPD makes up for high lumen in small range)
 
Last edited:

NorCalFor20

Smokes, lets go
Veteran
what are the increased red spectrum hps's you were talking about? has anyone ran a mh,cmh,and hps all together?
 
simba said:
1love.. those people.. unfort none of them have any documentation.. (sideby side vs the many supporting)
id go 2 cmh's if the area supports it..
remember you dont need overkill the plant is getting full spd which means more food from light and more energy etc to proses nutes to usable food and use it..
if ur going to add hps no mater what get a basic 400 hps from comercial supply house.. IE LU400

side note if youll notice the plant pictures being nocked mainly are ones by NEWBIES>> and its expected there first few runs to be iffy..
also when i first switched to cmh there was a bit of a simple learning curve.. IE shorter veg, silica needed, bit higher ppm..(within reason, plant gets hungrier off cmh,,)
i would say the newbies will master cmh or any grow style faster than a experienced grower as they have a hard time forgetting what they know to be fact under "old thoughts"
i have to admit i was one of those stubborn at first cause lumen etc hype about horti bulbs etc.. but now im passed the point of die hard supporter

as far as penetration.. hps ya has more lumens so technicly it has more Pen. however you have to have it higher than CMH>cause it will COOK your tops.. . so you loose Mass there (inv sqr law light Loose 4 times per equal distance)
and if you will notice under hps most are tall as can be.. under cmh with short veg (long veg not needed to mature plant full spd does that)
so you dont have to pen as much any ways..
so when u combine those two cmh has more enegy at plant level..(FULL SPD makes up for high lumen in small range)

currently 1 400 watt CMH offers me 25 watts per sq ft in my room.

My room is 2.5ft by 6.5ft, so it is very much so a rectangle.

Now, what I'm inferring from your post is that I should grab a 2nd CMH?

I 'could' always get a 600 watt HPS, but I dunno.

My main reason for adding a 2nd light is yield. Therefor my main concern with the 2nd light (be it HPS, CMH, 400w or 600w, though there is no 600w CMH) is yield.

Simply put, if I've already got 400 watts of CMH in my 6.5 ft by 2.5 ft room, what is going to increase the yields best, a 2nd 400 watt CMH, a 400 watt HPS (assume best bulb available), or a 600 watt HPS?

I realize comparing a 600 watt HPS to a 400 watt CMH isn't fair, but take into account my room size, and watts per sq ft.

A 400 watt CMH and a 600 watt HPS would mean 61 watts per sq ft

800 watts of CMH (or HPS, whatever mix) is 50 watts per sq ft.

Another thing is that this is all going to be run off of a 15 amp breaker, but I figure even 1000 total watts (1 CMH and 1 600w HPS)is still well within my "safe zone", even with an inline fan, and a few floros in the veg cab for vegging (eventually, as my veg cab is not up and running yet, and I am currently vegging in what will be the flowering room), though I cannot deny that 800 total watts (2 CMH or 1 CMH and 1 400w HPS)

One thing to consider is that I am running aircooled super sun 2's, with the ballast(s) located outside the grow room.

Again, with adding the 2nd light (which for me means buying a reflector/ballast/bulb) I am doing so purely to increase my yield, so what is going to give me the best yield in my room? What bulb?

Cannot overstress that yield is what I'm after.
 
Last edited:

simba

Sleeping Dragon
1 cmh in that No way it will at max single light source cover 3X4 if you have lets call it a "good reflector"
this is complex yet simple.. answer..
if you add another lets say hps it would be unwise to put it dead center as the losss of energy on either side of the 6.5' is to great...
and if you put it on one side of that room half the room will Lean to and bush on the CMH side)
so unless your willing to go to 2 hps then you do need another CMH.. in your setup you need your lamps several feet apart and that wont provide an even spectrum on the plants..(i have to find it but i had a tomato plant that had a actinic on one side of it and that side was Bush and other was LOL pitafull..when compared to actinic side..
if your after max yeild it woulda been better with 3-4 250 cmhs that would do the Y axis lets call it (parale to bulb) 2.5 nicely while giving you overlap on the X (perpendicular to bulb)

even if a 600 cmh was out in your setup no way could you use it
it would be overkill dead center and inverse square law of light.. would be less than if you had 2 250's (basically for our purposes. as i forget the exact outcome but gives u idea..)
the thing is the more area you cover with your lamp your lamp wattage requirement goes sky high (inv sqaur law)its better to use multi lamps..
its hard to get past the idea big is always better..
ive seen 600 watt CMH and its not for us(unless you mount Minimum 8' or hanging vertical with Many basically replacing 1kw hps verticals..thats the only way.. but we have to change some things.. you can get more yield out of more plants in same area that are mini xmas trees.. (no bush plants wasting space etc..)
and its to bright for us to be near.. the 400 dam near blinds you.. that shows lumen dont mean much when you see the cmh way brighter than a same watt hps.horti high lumen.. (cmh has the energy..plant seeas it same way.)
 
Last edited:
well, sounds like a 2nd CMH it is.

So currently I've got 1 400 watt CMH in a super sun 2 reflector covering the whole room, it's about in the middle.

I figure when I add a 2nd unit, we'll make it so they each cover about the same, 1 covering 1 half of the room, the other covering the other half. Makes sense? Sounds ok?

So I should definately go with a 2nd CMH, rather than HPS?

Then general idea I had was to aircool the reflectors, leave some slack on the ducting, keep them as close to the plants as I can, and just move them up as the plants grow.
 
Last edited:

MPL

Member
I would get a second CMH as well. You want the coverage in your room to be even, and that includes color as well as intensity.

Then, you could always do a side-by-side comparison of a 400w HPS vs a 400w CMH. :D

You should not need to aircool your 400w CMH lamps. I don't and my cabinet is tiny.

1love1earth said:
well, sounds like a 2nd CMH it is.

So currently I've got 1 400 watt CMH in a super sun 2 reflector covering the whole room, it's about in the middle.

I figure when I add a 2nd unit, we'll make it so they each cover about the same, 1 covering 1 half of the room, the other covering the other half. Makes sense? Sounds ok?

So I should definately go with a 2nd CMH, rather than HPS?

Then general idea I had was to aircool the reflectors, leave some slack on the ducting, keep them as close to the plants as I can, and just move them up as the plants grow.
 
I have 2 separate grows right now, both with 800w CMH. In one of them I initially put a 400W HPS instead of the second CMH and i switched the next day back to CMH b/c of the HUGE difference in the amount of heat that radiated below the hood. I would have had to have the HPS at least a few inches higher off the canopy than the CMH hood. Both were in SuperSun 2 reflectors.
 
it isn't aircooled now, but I figure why the heck not? I've got a reflector that aircools, and I'm running an inline fan for a carbon filter anyways, it'll just let me have my lights that much closer.
 

OsWiZzLe

Active member
I hope none of guys grow any strains with some hectic stretching.....because then you'll realize how whack the CMH is....those lights have to be like a a foot or closer at all times to use them properly...i cant believe how many people are jumping on this bandwagon....somebody please post up a picture of huge colas from CMH...let me see something that puts the HPS to shame.....
 
Top