cmh or hps question

I tried to grow a couple of times without much success mainly cause i was trying things gheto style. Going to change that this attempt an do things right. Thing is I have a chance thoughto buy a used but nice hps from a friend for cheap but he thinks i'd be better off spending money on a cmh bulb because he says its so much better than hps. Not sure if he's right;is cmh worth the money and do i have to buy a new socket for the cmh bulb if i get both? :leaf:
 

jeeba

Well-Known Member
A cmh bulb holds a fuller spectrum then a hps,so it will be better as a all around light you wont have to switch from Mh to Hps.If you do buy a Cmh make sure it is the proper position you need it , universal,horizontal,and vertical mount are your options and you have to use a magnetic ballast.Just a few things to take into consideration.There are alot of right ups about them take a looky around and make the best decision.Good Luck.
 

Brick Top

New Member
CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.


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darkdestruction420

Well-Known Member
cmh is better than normal hps in my experience(in addition to being better in the veg phase than a normal mh). however i would advise a high output spectrally enhanced hps bulb. They are all that i use for both stages as theyve performed the best for me . i will also say that imo the part about cmh bulbs running cooler than hps is to be frank b/s, i saw a drop of less than 2 degrees.
 
oh and can i use rainwater from outside or should i get only bottled water or just use house water?? confused;i dont have a pph meter :leaf:
 

massah

Well-Known Member
MH and HPS bulbs usually use the same E39 sockets, but the ballast has to be compatible if you are going to run straight CMH bulbs...they make conversion CMH bulbs that go in HPS ballasts...so unless your HPS ballast is a switchable one to run a MH bulb then you have to get a conversion bulb :)
 

cowboylogic

Well-Known Member
CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.


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Sorry none grower. CMH have been proven very effective for growing plants. And OP use the rain water, great choice....
 

jeeba

Well-Known Member
CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.


View attachment 2034236
Bricktop are you saying that a hps is better for veg than a cmh?Because the conversion bulbs from Hps to Mh seem to be around 100$ and the cmh bulb is around 50.I believe.
 

massah

Well-Known Member
oh and can i use rainwater from outside or should i get only bottled water or just use house water?? confused;i dont have a pph meter :leaf:
you can use any of the above types of water...unless your "house water" is complete and utter shit...if you are growing in good prelimed soil you don't have to really worry about the ph as the soil takes care of that for you :)
 

cowboylogic

Well-Known Member
Bricktop are you saying that a hps is better for veg than a cmh?Because the conversion bulbs from Hps to Mh seem to be around 100$ and the cmh bulb is around 50.I believe.
If you have a magnetic HPS ballast then conversion bulbs are not needed, just screw in a regular MH bulb with no worries. Conversion bulbs are just another way to get into your pockets........this is for 250 watt and higher ballasts. Below 250 has a few of its own rules.....
 

jeeba

Well-Known Member
Ummmmm that is just bad info if you plug a straight up metal halide in a Hps ballast things might go boom boom.I believe thats why they make conversion bulbs and switchable ballasts.
If you have a magnetic HPS ballast then conversion bulbs are not needed, just screw in a regular MH bulb with no worries. Conversion bulbs are just another way to get into your pockets........this is for 250 watt and higher ballasts. Below 250 has a few of its own rules.....
 

skunkd0c

Well-Known Member
the op said he tried to grow before without too much success, i do not think obsessing over what bulb to use is going to make difference for him or help him in the long run
weather he uses hps cmh or some kind of grolux bulb in all honestly the difference would be barely noticeable if at all

he would better spend his time concentrating on a much wider range of basic growing knowledge

peace :)
 

cowboylogic

Well-Known Member
Ummmmm that is just bad info if you plug a straight up metal halide in a Hps ballast things might go boom boom.I believe thats why they make conversion bulbs and switchable ballasts.
What I said is safe info. The only difference between a MH and HPS ballast is the igniter And the igniter only fires when called for the initial firing of a HPS/CMH bulbs. You can spend the extra money on convertible ballasts and conversion bulbs if you like, but not needed. Just get a mag HPS ballast and use CMH, MH or HPS bulbs perfectly safe and effective.......
 

jeeba

Well-Known Member
I have never heard of this can anyone validate?Sorry for being sceptical but alot of the shit on the web is bad info.
What I said is safe info. The only difference between a MH and HPS ballast is the igniter And the igniter only fires when called upon to fire initial firing of a HPS bulb. You can spend the extra money on convertible ballasts and conversion bulbs if you like, but not needed. Just get a mag HPS ballast and use CMH, MH or HPS bulbs perfectly safe and effective.......
 
ok i'll get a new socket;don't want to burn the babies. :cuss:that's cause i didn't want to spend the money then and didn't try to hard skunk. And i grew 2 plants outside this winter that was fire;i can do it now that i have all the money i need to get everything i'd ever want to grow more fire. u are just jealous maybe?
 

Brick Top

New Member
Originally Posted by Brick Top

CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.

Bricktop are you saying that a hps is better for veg than a cmh?Because the conversion bulbs from Hps to Mh seem to be around 100$ and the cmh bulb is around 50.I believe.
Uuuuuhhhhhhhhhhhhhhhh .... no. I did not come anywhere close to saying anything of the sort.


The question began; "I tried to grow a couple of times without much success mainly cause i was trying things gheto style. Going to change that this attempt an do things right."


Well, if he wants to; "do things right" than my answer was self explanatory.

CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.


Look at the light spectrum put out by a CMH bulb (in double graph with HPS spectrum also). Then look at the graphs that shows what wavelengths/spectrum that Chlorophyll A uses, one is a still graph and the other a GIF.

The greenish line on the GIF shows the rate of photosynthesis. There are two high points. The one to the left is plants in veg and the one to the right is plants in flower. They show how much of each wavelength/spectrum plants use during different stages of growth.


The black line shows the absorbance of
Chlorophyll A. The high point, the spike to the left side (of both the still and moving graphs) are plants in veg and the high point, the spike to the right are plants in flower.

A 6500K MH bulb best matches the peak in veg without creating large amounts of hardly used, or totally unused light, such as a CMH creates. A HPS does the same thing for when plants are in flower.

A bulb of any wattage will only put out 'X' amount of light. Now what makes more sense, to use bulbs that only put out the wavelength/spectrum that plants need and will use the most while in either veg or flower, dedicating their entire light output to the greatest need plants have during each phase of growth, or use a bulb that creates less of each wavelength/spectrum plants need during each phase of growth, but it creates large amounts of wavelength/spectrum that plants either do not need or do not use, much of it at any stage of growth, let alone during each specific stage of either veg or flower?

If the question was, I want to use one type of bulb and only one type of bulb from start to finish, so what should I use? I would suggest a CMH.

But that was not the question. It was between CHM and HPS, but without any thought about MH and the combination of MH for veg and HPS for flower.

Since it was said that he wants; "to do things right," suggesting a third, and far better option, was only logical.


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jeeba

Well-Known Member
Uuuuuhhhhhhhhhhhhhhhh .... no. I did not come anywhere close to saying anything of the sort.


The question began; "I tried to grow a couple of times without much success mainly cause i was trying things gheto style. Going to change that this attempt an do things right."


Well, if he wants to; "do things right" than my answer was self explanatory.

CMH is a broad spectrum bulb. They put off a lot of light spectrum/wavelength that plants don't use and or hardly use. That is not beneficial for plants. Didnt mean to put words in your mouth.

If you want good lighting purchase a HID that will allow you to use a MH (6500K) bulb for vegging and a HPS for flowering.


Look at the light spectrum put out by a CMH bulb (in double graph with HPS spectrum also). Then look at the graphs that shows what wavelengths/spectrum that Chlorophyll A uses, one is a still graph and the other a GIF.

The greenish line on the GIF shows the rate of photosynthesis. There are two high points. The one to the left is plants in veg and the one to the right is plants in flower. They show how much of each wavelength/spectrum plants use during different stages of growth.


The black line shows the absorbance of
Chlorophyll A. The high point, the spike to the left side (of both the still and moving graphs) are plants in veg and the high point, the spike to the right are plants in flower.

A 6500K MH bulb best matched the peak in veg without creating large amounts of hardly used, or totally unused light, such as a CMH creates. A HPS does the same thing for when plants are in flower.

A bulb of any wattage will only put out 'X' amount of light. Now what makes more sense, to use bulbs that only put out the wavelength/spectrum that plants need and will use the most while in either veg or flower, dedicating their entire light output to the greatest need plants have during each phase of growth, or use a bulb that creates less of each wavelength/spectrum plants need during each phase of growth, but it creates large amounts of wavelength/spectrum that plants either do not need or do not use, much of it at any stage of growth, let alone during each specific stage of either veg or flower?

If the question was, I want to use one type of bulb and only one type of bulb from start to finish, so what should I use? I would suggest a CMH.

But that was not the question. It was between CHM and HPS, but without any thought about MH and the combination of MH for veg and HPS for flower.

Since it was said that he wants; "to do things right," suggesting a third, and far better option, was only logical.


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Ok sorry I misread and misunderstood,thanks for ellaborating for me.
 
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