MH for Flowering?

[Brick Top]

So how is an HPS better? I mean that chart compares CMH and HPS and the CMH looks a lot better to me especially since I already know an HPS is not needed in anyway, a MH with more colors sounds to be just the bees knees.

Of the entire light spectrum only 44% is visible light. Plants only use visible light and of that they mainly only use two fairly narrow ranges of it. So precisely what good is it for watts to be burned to create spectrum ranges that plants do not use or hardly use?

Chlorophyll does not absorb all wavelenghts of visible light equally. Chlorophyll a, the most important light-absorbing pigment in plants, does not absorb light in the green part of the spectrum, so the green from a CMH is useless because light in the green wavelength is reflected.

Light absorption by chlorophyll a is at a maximum at two points, between 430 and 662nm, and, those are two 'peaks.' There is not near equal amounts of light absorption of the wavelength between them. So that's another part of the CMH light spectrum that is basically wasted wattage being burned to create something plants use extremely little of. And on either side of the two peaks the light adsorption rate again greatly diminishes because, again, it is not in a range chlorophyll a absorbs.

Since that is the case, please clarify why; "more colors sounds to be just the bees knees" to you.



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[Icannabis]

I like to get those gamma ray's on my plants to hulk them up...lol Try it for yourself if you don't like what happens try something different...I know a guy that swears by CMH...I don't listen to him because all he talks about is back in the day...this and that...plus he refers to the new weed as hippie killer...enough of that...good growing

 

[Thedillestpickle]

"Gross orange light" or not, a HPS puts out more of the light spectrum that plants use in flower than a CMH, which is a full spectrum bulb that is always putting out at least some amount of light spectrum that plants either do not use or do not always need.

I really don't like that chart comparrison, which I have now seen in a number of places. It's false advertising, looking at that chart without any other knowledge one would believe that the light on the left is producing almost 10 times more light! It's a lie, I'm not sure how this chart was calculated but theres no way its producing that much light in all of those ranges of the spectrum.
Ive heard that MH was the only option for indoor growing back in the days before HPS came around and the growers did quite well, but it is known fact that HPS works better than MH.

I know that MH produces UV b but I'm not sure that any of that is actually being emitted by the light as the glass is usually treated to filter out that wavelength(for safety). Someone correct me if I'm wrong on that, I would like to know if I can use MH as a UV supplement

 

[Brick Top]

I really don't like that chart comparrison, which I have now seen in a number of places. It's false advertising, looking at that chart without any other knowledge one would believe that the light on the left is producing almost 10 times more light! It's a lie, I'm not sure how this chart was calculated but theres no way its producing that much light in all of those ranges of the spectrum.
Ive heard that MH was the only option for indoor growing back in the days before HPS came around and the growers did quite well, but it is known fact that HPS works better than MH.

The chart on the left is for a Ceramic Metal Halide, not a standard Metal Halide, so there will be some differences between the light spectrum each puts out, with the Ceramic Metal Halide being a broader range bulb.


But the point remains, why waste some percentage of a bulb's ability to put out light/spectrum on wavelengths that plants either do not use at all or use extremely little of when instead they can be flooded with the wavelengths they need and use the most? So that means the best someone can give their plants is MH for veg (6500K, not others that are closer to HPS wavelengths) and HPS for flower.

 

[Brick Top]

I like to get those gamma ray's on my plants to hulk them up...lol Try it for yourself if you don't like what happens try something different...

That was a joke, right? I mean, the; "lol" was saying that you were pulling people's leg, right?


Plants use light between 400-700 nm wavelength (or 1.7-3 eV), i.e. the same energy level that we see with our eyes. Gamma radiation is way shorter in wavelength (more energetic) with energies of keV to MeV.


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[Thedillestpickle]

That was a joke, right? I mean, the; "lol" was saying that you were pulling people's leg, right?


Plants use light between 400-700 nm wavelength (or 1.7-3 eV), i.e. the same energy level that we see with our eyes. Gamma radiation is way shorter in wavelength (more energetic) with energies of keV to MeV.


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Haha Bricktop you're always so serious! that was definately a joke lol
I like how you always come through with the science though, its very helpfull.
You missed my point when I said I didnt like that chart it was because I believe it to be a misrepresentation of the amount of lumens that the CMH produce. I fully agree with your statement that it is a waste of light/energy/money. I think people may be mislead by that chart however because it shows quite impressive amounts of ALL wavelengths. It appears to produce 10 times the amount of light as its counterpart MH, which I'm sure we all know is impossible

Bricktop what's your take on UV lighting?

 

[missnu]

How is the spectrum not used by the plants...I use only the blue throughout and everything looks awesome. No difference in growth...

 

[missnu]

Here is the deal...HPS lights put out more lumens, but only of the one color range...so while your plants do need the other wavelengths they aren't able to get them...does it hurt the plant? No---or my MH throughout the whole grow would never work...so they made a bulb that has the lumens of an HPS and some of the colors of the MH...It puts out all wavelengths all the time. I just don't see how HPS is needed at all...Like I said I quit using mine and am having no issues with it...so I figured out a CMH which seems to me to be an HPS bulb with a better light spectrum and that is the point...it is supposed to be MH and HPS all in one. Either way it should be delivered soon and I'll just start a journal or something...I keep one for personal use...I guess I could make one on here.

 

[Brick Top]

Haha Bricktop you're always so serious! that was definately a joke lol
I like how you always come through with the science though, its very helpfull.
You missed my point when I said I didnt like that chart it was because I believe it to be a misrepresentation of the amount of lumens that the CMH produce. I fully agree with your statement that it is a waste of light/energy/money. I think people may be mislead by that chart however because it shows quite impressive amounts of ALL wavelengths. It appears to produce 10 times the amount of light as its counterpart MH, which I'm sure we all know is impossible

Bricktop what's your take on UV lighting?

I did catch your point about the chart, but then I am willing to give it the benefit of the doubt in that it is about a specific manufacturer's bulb, if I remember right, and if you do a comparison of any manufacturer's bulbs, MH or HPS, there will be a fair degree of variance between some. I am not saying I would swear to it's accuracy, but I believe it is possible.


As for UV lighting ... if you don't have it, add it. Pick up some Mega Ray UVB lights and watch the trichs spring up everywhere and grow big and enjoy the additional potency.

http://www.reptileuv.com/megaray-products.php

 

[Brick Top]

How is the spectrum not used by the plants...I use only the blue throughout and everything looks awesome. No difference in growth...

If you only use; "the blue throughout" your grows than how do you know there is; "no difference in growth?"

I am not sure what you meant by; "the spectrum," but as I already stated, "Chlorophyll does not absorb all wavelenghts of visible light equally. Chlorophyll a, the most important light-absorbing pigment in plants, does not absorb light in the green part of the spectrum, so the green from a CMH is useless because light in the green wavelength is reflected.

Light absorption by chlorophyll a is at a maximum at two points, between 430 and 662nm, and, those are two 'peaks.' There is not near equal amounts of light absorption of the wavelength between them. So that's another part of the CMH light spectrum that is basically wasted wattage being burned to create something plants use extremely little of. And on either side of the two peaks the light absorption rate again greatly diminishes because, again, it is not in a range chlorophyll a absorbs."

So, is; "the spectrum" something other or outside of what I mentioned?

Try looking at it in the most simple of terms. A bulb can only put off a certain amount of light. What is the value of portions of the light it puts off not being of value to plants and by putting off that light it is incapable of putting off as much of the light plants use, as it could if that would be all one put off?

 

[missnu]

Well I was using the MH for veg and the HPS for flower, but then I decided I didn't really like the heat of the HPS so I quit using it...I had done a few grows with the HPS and now a I am on my second without it, and there is no difference in the buds, or if it is it isn't a noticeable difference in yield, although I do notice that with the MH the plants seem to be more resinous...then again I am getting better each time, so perhaps I switched off the HPS and my buds are comparable because I have gotten better with understanding nutes and soil biology...All I know is that I don't see any difference between what I yielded with the HPS and what I have yielded with the MH...If I still had an HPS bulb I could run the same strains through with it next time about...but I don't.. So I will keep using my MH for veg and I am going to use the CMH for flower...What about the fact that plants need more than just orange light even during flowering? A good bit of that light is wasted because the plant has the ability to use other colors but they aren't there. it seems to me that it should give the benefit of both...no matter what bulb you use there is going to be wasted light...and if plants do use other colors during flowering then why do we only give them orange... I mean obviously the plants use other colors during flower, or my plants wouldn't be flowering as well as they are right? I mean if all they used was orange and you give them no orange there would be repercussions...but here I am sporting only very blue light and everything looks great. And a good many people use MH for flowering, but everyone says ohhhh noooo you have to use orange light from a HPS? Why I say? Why?

 

[missnu]

The reason HPS is thought to be better is that they produce more lumens...but what if they could get a bulb to put off that much light, but in a more variated spectrum...would it not be even better and possibly stronger than an HPS? Since the light value is still there as well as more usable light available to the plant.

 

[Brick Top]

A good bit of that light is wasted because the plant has the ability to use other colors but they aren't there. it seems to me that it should give the benefit of both...no matter what bulb you use there is going to be wasted light...and if plants do use other colors during flowering then why do we only give them orange... I mean obviously the plants use other colors during flower, or my plants wouldn't be flowering as well as they are right? I mean if all they used was orange and you give them no orange there would be repercussions...but here I am sporting only very blue light and everything looks great. And a good many people use MH for flowering, but everyone says ohhhh noooo you have to use orange light from a HPS? Why I say? Why?

Did you look at the rate of photosynthesis of plants according to light spectrum, as pertains to vegging and flowering? What chlorophyll 'A' almost exclusively uses is blue in veg and orange/red in flower. So what value is found with instead giving them a different spectrum or a broader spectrum?

Look at the green/greenish line, that's what chlorophyll 'A' uses and when it uses it, and when the plants want and need it. Also look at the two spikes in the other lines, and that's MH and HPS output. You might happen to notice that they are rather close to what the plants want and need the most during those particular stages of growth. What value is green light, which is reflected? What value is the darker reds that are virtually unused?

Personally I don't care what you use. You can use birthday candles for all I care. But you will mislead those who do not know any better by making inaccurate claims of MH, including CMH, as being as good or nearly as good for flowering as HPS.


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[missnu]

Why...if these CMH are made to contend against HPS...who is to say that they are worse or better. It is a difference of opinion...I never say that this is the way it is, but this is what i am doing and it works for me.

 

[missnu]

No one has to follow my example...

 

[Pearl00S4]

I am just wondering if anyone has ever tried this or knows something about it. So the question is: Can you use an MH grow light for flowering? Say for example a 400w MH. Just looking for input

thats what im flowering with. works fineView attachment 2030213i just chopped these down a few days ago off MH, 1000w though

 

[Brick Top]

Why...if these CMH are made to contend against HPS...who is to say that they are worse or better. It is a difference of opinion..

The difference in light spectrum and how plants/chlorophyll 'A' uses light is NOT; "a difference of opinion." A; "difference of opinion" is only created and then exists IF someone ignores the facts and instead insists on believing whatever it is they prefer to believe, and then wants to argue it as if it is fact.

 

[Brick Top]

No one has to follow my example...

No, no one; "has" to follow your example. But when you preach that something is as good as, or better, than something else, when it is not, given the number of less experienced growers here and the continual flood of noobies, some are going to think you know what you are talking about and they will then make the mistake of following your; "example."

 

[Thedillestpickle]

Missnu, I would think using a ratio of MH:HPS is what your after more than what the CMH can offer you. If you were to use a smaller MH along with your larger HPS you would get the colour spectrum you want and not be waisting lumens on green and other unusable colours

What I can't understand is why plants would need one spectrum during one phase and another spectrum during the next phase. I suppose I can understand with high latitude plants because it would be a survival mechanism to make the most of the orange light during autumn. But with equitorial plants they would recieve blue light all season, so why wouldn't they make just as much use of it? Or is it more of a concern of "triggering" flower production than providing useable light? Perhaps given only blue light a plant doesn't sense the autumn coming as well and feels less need to fower?(hormone related, instead of metabolism related)

Bricktop, given the questions I just asked and their implications would you suspect something closer to a 50/50 MH/HPS ratio would work best for more equitorial strains, as this would more closely mimick the light spectrum those plants would receive in their natural habitat?

Oh and thank you for that link, I will now be implementing UV lighting for the last 4 weeks of flowering

 

[RawBudzski]

Yes I have used a 600w MH for bloom, worked, not as dense as my hps. I pulled too early. & for some reason I want to hear more about these gamma rays from BT kekekekeke

Knowledge FTW !