MH vs HPS in bloom

[Pinball Wizard]

I like the different kelvin temps of MH bulbs 3000K thru 7000k

 

[the gnome]

I like the different kelvin temps of MH bulbs View Image 3000K thru 7000k

View Image

i agree pinball
the $21 Mh I'm using in my current grow is a 4000K.
it's a very middle of the road spectrum
looks more like natural sunlight over any other HID lamp
Ive ever used


and I get these results using it on my tse fly and otm-ibg

 

[indoor/outdoor]

I like hps,because it puts out more lumens per watt than mh,thats why it yields better.But the mh spectrum is nicer to look at the plants and take pics w/ the lights on.Great job on the Blue Dream

 

[psyphish]

I like hps,because it puts out more lumens per watt than mh,thats why it yields better.But the mh spectrum is nicer to look at the plants and take pics w/ the lights on.Great job on the Blue Dream

Lumens have nothing to do with yield. The reason hps produces more is because it has a higher output of red than your basic MH. The newer 315w ceramic metal halides yield about the same as 600w hps, but only have 36000 lumens.

 

[Buds Bundy]

so has anyone tried a PlantMax Dual Arc 1000 watt bulb....

110,000 lumens has both spectrums in one bulb...600 watt HPS + a 400 watt MH... emitted from one bulb.... runs on a 1000 watt ballast

The lumen rating for bulbs are BS. Thats the initial lumens that you get in the first 100 hours of firing.

400W MH is aprox 35K lumens
600W HPS is parox 90K lumens

Its cheaper to buy those two bulbs than some of the dual arc bulbs and if one burns out you don't have to replace the whole thing.

 

[Ilikecookies]

Lumens have nothing to do with yield. The reason hps produces more is because it has a higher output of red than your basic MH. The newer 315w ceramic metal halides yield about the same as 600w hps, but only have 36000 lumens.

This is the opposite of true.
The reason HPS yields well is because of the lumens, red has little to do with yield.
In fact a MH with the same lumen rating as an HPS will yield better.

 

[rxthc]

I am under the impression that during flowering( in the fall) the sun is lower in the horizon and hence has greater ozone to trvel through, there by changing the spectrum of the sunlight that reaches the earth and that plants over time have become sensitive to this color change so much so that without changing day length but changing spectrum can trigger flowering. However I have seen plants grown from clone to bud with nothing but MH bulbs with satisfactory end results.

 

[MEnSouRdeeZ]

The plants are not signalled to bloom by red light...... They are signalled by the number of hours of dark.

I think I read that mj's reproductive clock/bloom phase/morphogenesis is controlled by 760nm light (or absence thereof)

so in theory you could introduce light lacking 760nm before and after regular full spectrum lighting photoperiod without disturbing reproductive cycle progress. think twilight (in more distant latitudes, before and after sun passes horizon). this would make sense as 760nm light like other red/far red has less propensity to diffuse i.e. it goes straight with less likely hood of scattering. so the sun would need to be directly visible to the plant...seems a more precise clock/trigger than any old light (bright moon?)
2c

 

[Azeotrope]

Ilikecookies - Lumens have absolutely NOTHING to do with plant lighting or plant growth. It is about photons........ Lumens is a measure of light photons in a range that the human eye is sensitive and not what should be considered when evaluating a light source.

 

[DrFever]

Ilikecookies - Lumens have absolutely NOTHING to do with plant lighting or plant growth. It is about photons........ Lumens is a measure of light photons in a range that the human eye is sensitive and not what should be considered when evaluating a light source.

you need to think of lumens as the Horse power that drives the plant


Lumens is a measurement of the amount light, the intensity it projects, the brightness and that's usually measured in hundreds of lumens. I don't know where the top of the scale is but the new brighter, Ecosmart CFL lamps I just changed over to in my home advertise that they generate 850 lumens of light while consuming only 14 watts of electricity. Now you don't have to light a match to find the damned things at night when they're turned on like their earlier predecessors. My wife used to bitch that the old ones being too dim to read under but now she complains that the new ones are too bright. Go figure. Now let's consider the color of the light they're producing.
Color, frequency or temperature of the light it produces is measured when it's run through a prism and seen in the available spectrum of colors. It’s measured in Kelvins; K's. These new lamps I bought are rated at 4,800K's, which is pretty close to the 5,000K green T-5 grow lamps I use for start of cuttings and vegging. The lower the K's, the redder and the warmer the light. The higher the K's the cooler the light and the color goes from green to blue. Cool, green to blue light is for vegetative growth and warm red light is for flowering. Got that? If you can keep that straight think about what the sun produces during the year. In the spring and early summer the light is bright and cool, it has a higher K rating number; it's greener toward blue and our plants grow.

And like someone posted on top about 315 watt CMH yielding more then a 600 watt HPS could you please show us some side by side grows for comparison???? cause i would prob bet that even tho CMH are doing well its still far off from blowing a 600 out of the water like comparing a 400 watt grow to a 1000 watt bottom line wattage per Sq foot and luminious power is what its all about for yield and overall plant growth

 

[Hash Zeppelin]

I am under the impression that during flowering( in the fall) the sun is lower in the horizon and hence has greater ozone to trvel through, there by changing the spectrum of the sunlight that reaches the earth and that plants over time have become sensitive to this color change so much so that without changing day length but changing spectrum can trigger flowering. However I have seen plants grown from clone to bud with nothing but MH bulbs with satisfactory end results.

this raises an interesting point. I guess a good experiment to test this is do light deprivation grows in the summer in a green house, vs a regular fall harvest in another green house, and do this a minimum of 3 times with at least 9 strains from different linage. You would need to have the nutrient schedule for each strain dialed in well. There cant be any other variables to make it scientifically valid.

 

[Ilikecookies]

The color of the sun changes very little during the season, and plants absorb the majority of their light at narrow bands in the spectrum, and the color of the sun is....????
It's not even close to that of an HPS, it is closer to the color of a MH.

HPS can be a very important part of plant growth, but it is as a supplement to the sun, or as a compliment to a sun-colored light.
HPS lighting became popular because of it's efficiency, and it's brightness, but read any true science document about plants, plant lighting, and/or plant growth and they will say that as a primary source of light MH is the best.

There is actually very little red light put out by an HPS that is useful to plants, the majority is far red, and that is used mostly for a signal to plants and as heat, less so as a growth factor.

 

[Azeotrope]

Lumens is a measurement of light output at nm points in the spectrum that the human eye is sensitive to. Not the amount of energy the bulb puts out that plants are sensitive to.

It is better to examine the points of high output by a bulb (spectrum output breakdown) as it relates to what a plant uses in the many photosynthetic processes that occur within the plant tissue. Measuring photon output at all different wavelengths against the plant sensitivity curve is a very good start.

 

[Stonefree69]

Lumens is a measurement of light output at nm points in the spectrum that the human eye is sensitive to. Not the amount of energy the bulb puts out that plants are sensitive to.

It is better to examine the points of high output by a bulb (spectrum output breakdown) as it relates to what a plant uses in the many photosynthetic processes that occur within the plant tissue. Measuring photon output at all different wavelengths against the plant sensitivity curve is a very good start.

IOW PAR is a good way. PAR is measure in Photosynthetic Photon Flux Density (PPFD) or umol/m2/second.

I had posted this in Growroom Lighting regarding PAR and measuring light: At midday in mid summer the sun can reach around : 2,000 umol/m2/sec (or PAR/PPFD) = 9,800 foot candles = 1,060 watts/m^2 = 98.5 watts/sq ft = 105,486 LUX = 9,800 lumens/sq ft. This varies with latitude but's a good guide for plants. There seems to be diminishing returns with light output past 6,500 foot candles or lumens/sq ft. Also note that all these different measurements listed are not true 1:1 conversions as they can measure different wavelengths in the spectrum (especially with PAR and the other measurements as PAR is more selective of wavelength). Here a good reference: Light Measurement Full sun is measured for a reasonable equivalence.

Also further to support MH and higher wavelength light like blue that whazzup was saying is the UVB lighting or reptile lights. Lots of people report more resin and trichomes and better quality bud. Just don't overdo UVB as it can also reduce your yields.

 

[whazzup]

Lol blue is higher frequency, so lower wave length .

Lumens are indeed for human as Azeotrope stated and have nothing to do with plant response. A high lumens lamp only indicates that it probably has lots of light around 550 nm where the human eye is most sensitive.

Spectrum doesn't change much over the seasons and one might even argue that in the summer you have more blue light, due to the blue skies (which are blue btw because of the diffuse blue light breaking on entrance of the atmosphere).

Fortunately the sun does not produce 2000 umol all day and doesn't even reach it every day in most places on earth, so 2000 umol is not a good aim. Look more for the dli.

Plants always do best under a full spectrum. Photosynthesis is driven by photon count, so a lamp with a higher photon output will produce a better yield. Quantity is one, quality is two. So while HPS still is the absolute winner when it comes to producing photons per watt, the quality of the spectrum is of influence too and will define the quality of the crop.

 

[Stonefree69]

Lol blue is higher frequency, so lower wave length .

Lumens are indeed for human as Azeotrope stated and have nothing to do with plant response. A high lumens lamp only indicates that it probably has lots of light around 550 nm where the human eye is most sensitive.

Spectrum doesn't change much over the seasons and one might even argue that in the summer you have more blue light, due to the blue skies (which are blue btw because of the diffuse blue light breaking on entrance of the atmosphere).

Fortunately the sun does not produce 2000 umol all day and doesn't even reach it every day in most places on earth, so 2000 umol is not a good aim. Look more for the dli.

Plants always do best under a full spectrum. Photosynthesis is driven by photon count, so a lamp with a higher photon output will produce a better yield. Quantity is one, quality is two. So while HPS still is the absolute winner when it comes to producing photons per watt, the quality of the spectrum is of influence too and will define the quality of the crop.

Duh yeah sorry my bad whazzup I was thinking higher frequency and realize the inverse relationship number between higher frequency and shorter wavelength. I agree the full spectrum is what plants like, just like the sun although it uses different wavelengths more efficiently (like red being more efficient eg at 660-680 nm). The ones who have it dialed for yield and quality seem to use both as in a 2-3:1 hps/mh ratio. Thanks for the heads up.

 

[Adze]

Small correction: "waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths"
Please check it if you doubt me.

 

[DrFever]

We can sit here all day blowing BS up each others ass scientifically speaking
One of the most important factors when it comes to plant growth is light. The amount of light, the quality of that light and the duration of the light all affect plant growth. For example, plants exposed to more intense light for longer periods will thrive up to a point; but plants won't do as well if they're constantly exposed to light, nor will they thrive if the light they receive is too weak in intensity
and for those that think lumens means nothing here some lighting 101 for you
Visible light, which is the light humans see, and plants are bound to each other because of energy. Light energy falling on a plant is turned into chemical energy within that plant via a process known as photosynthesis. The plant uses chemical energy to power its growth and reproductive activities. Plants can't survive without light. However, plants only use certain colors within visible light to make energy and they disregard the others, reflecting them away. .... so again get the visible lighting you can see being no good for the plant out of your head its Horsepower driving the plant and again it uses some of the visible light dam why is it so important to have white surfaces so to reflect and help room to be as lit as possible

Plants exposed to low light tend to grow spindly. Plants exposed to brighter light grow larger and stouter leaves and more branches. The duration of light falling on a plant is less important than the intensity, and most plants do well on about 12 hours up to about 16 hours per day. However, some plants, such as the poinsettia, won't flower or bud if they receive more than 11 hours of light.

In order to make sure plants grow their best, the light they receive needs to be of sufficient and appropriate intensity and quality. Outdoor plants are adapted to make optimal use of the sunlight falling upon them. An outdoor plant native to a specific region in the country, for example, has adapted itself to day length and light intensity conditions. For indoor plants, brighter lighting containing at least blue light with a little bit of red light is best to assure healthy plant growth.

Again way people are talking on here lumens meaning nothing and light spectrum is like saying 250 watt perfect spectrum light will do better then a 1000 watt hid cause of the 110,000 + lumens meaning nothing ok think what u like

would you look at all the wasted iight the sun produces that i can see and is no good for our plants hahahah

 

[daylighting]

Plants absorb more light in the 600-660nm range than any other kind regardless of cycle, and continue to use blue light even in flowering.

MH produces less red light (obviously), and the sun provides light across all spectra. Plants actually absorb all kinds of light, even a little green, but the most important is in the 440nm range and 660nm range.

Where HPS (and CFL in my case) is lacking is in the 660nm range, so I'm looking to supplement 660nm with LED. HPS, a little cool and warm CFL and some 660nm LED would kick serious tail.

For veg I'd want some blue, but more red, and less blue and even more red in flowering, but still both, plus the additional wavelengths in less intensity. I'd want that 660nm going regardless as it is highly desirable and missing from both HPS and MH spectra.

 

[daylighting]

PAR curve against sunlight:

Different types of light compared to PAR:

EDIT: the PAR curve on the second pic is skewed too far to the right, but you get the general idea.