HPS vs MH ! HPS overrated ???
- Thread starter TommyHobby
- Start date
homebrewer
Well-Known Member
I've got the 600 HPS is someone wants to put together a challenge.
kingofqueen
Well-Known Member
Would still be interesting to see the difference in buds Homebrewers buds are awesome looking ! Just need another good grower using mh for flower !
kingofqueen
Well-Known Member
Whats the difference on the color charts for ceramic mh versus regular mh? I hear that cmh runs cooler is why some ppl use it and produces vivid color for viewing your plants during flowering .
TommyHobby
Active Member
.... and then there's SULFUR PLASMA technology......
mygirls
Medical Marijuana (MOD)
thats why the MH looks brighter because of the blue spectrum but in all actuality the HPS is brighter.
Some things to keep in mind when debating MH vs HPS.
HPS was developed to be a visually bright light with little attention to the actual color of the light. It was designed primarily for streetlights and parking lots where you want bright lights, but you really don't care about the quality of that light.
MH was developed for applications which required a strong light source, but where the quality of the light (the color spectrum) was important. This is commonly used in warehouses, commercial displays and other similar applications.
As a result, you can't simply take one spectrum chart for each and compare the two. Since there is not nearly the color range in HPS bulbs, you will find the HPS color chart is roughly what you will get. With MH you have hundreds (if not thousands) of bulb choices that vary dramatically based on spectrum. Every bulb can have a dramatically different spectral breakdown, so those comparisons are somewhat effective for comparing that particular MH bulb to a HPS, they are no where near enough to make any blanket statement comparing the two technologies.
Lumen output is cool if you're growing people in your closet. However, most of us grow plants, so we should be talking about PAR ratings...
HPS was developed to be a visually bright light with little attention to the actual color of the light. It was designed primarily for streetlights and parking lots where you want bright lights, but you really don't care about the quality of that light.
MH was developed for applications which required a strong light source, but where the quality of the light (the color spectrum) was important. This is commonly used in warehouses, commercial displays and other similar applications.
As a result, you can't simply take one spectrum chart for each and compare the two. Since there is not nearly the color range in HPS bulbs, you will find the HPS color chart is roughly what you will get. With MH you have hundreds (if not thousands) of bulb choices that vary dramatically based on spectrum. Every bulb can have a dramatically different spectral breakdown, so those comparisons are somewhat effective for comparing that particular MH bulb to a HPS, they are no where near enough to make any blanket statement comparing the two technologies.
Lumen output is cool if you're growing people in your closet. However, most of us grow plants, so we should be talking about PAR ratings...
nathenking
Well-Known Member
HPS with out a doubt.... Chlorophyl absorption rate is the highest during the red wave length... There are 2 types of chlorophyl, a and b, a is the primary chlorophyl and absorbs the red spectrum (measured in nm) This is just off the top of my head, I would have to get out my bot book from a couple semesters ago.
TommyHobby
Active Member
how do u explain the graph in the first post?
Yep, A and B, each of them have 2 peaks. A peaks at 455 and 625nm, B peaks at 475 and 665nm. Testing has shown that the higher wavelengths (red spectrum) are slightly more efficient than the blue, but that isn't to say you should give just the higher wavelengths. The most efficient production of sugars will be from combining all photosynthetic peaks, possibly going slightly higher on the red, but not neglecting the blues. From looking at seasonal spectral changes in the sun, in autumn the sunlight will shift more toward higher wavelengths, so flowering is typically accompanied by higher 625-665nm levels than earlier in the season when going through veg. This doesn't mean that it cuts out the 455-475nm peaks, simply that the intensity of light is stronger in the higher wavelengths.
I got a request to elaborate on PAR a little. There is a lot of very scientific info on PAR and photosynthesis online, so my best advice is to do some research. The subject of light spectrum is a broad and complicated field. I am by no means an expert, I simply have spent a lot of time over the last few years doing research on the subject.
To give an overview. When us humans think about light we think about how bright something is to us. How much it illuminates, and how far that illumination penetrates. This is the idea behind luminosity, which is the basis for many of the ways that humans quantify the intensity of a light source (luminous energy, luminous flux, luminous intensity, luminance, illuminance, luminous emittance, luminous efficacy, etc...). Basically lumens are a measure of light in the spectrum peaking at roughly 550nm, and sharply dropping off. This is what we see and makes a lot of sense when you are talking about how bright a light source appears to us.
Plants, on the other hand, see a much wider range of light colors than we do (excluding greens). When we talk about a plant 'seeing' what we really mean is that it is able to perform photosynthesis. As I mentioned before, photosynthesis (the production of sugars) peaks at two points for each type of chlorophyll, of which there are two. PAR (photosynthetic active radiation) is a measurement of the intensity of a light source with peaks around 450nm and 665nm. The levels will taper down from a high blue to a low green, then back to a high red; following the spectrum of light that plants are able to use for photosynthesis. Instead of measuring how bright we see a light source, it is measuring how bright the sources of photosynthetic light are.
The end result of all this is that most lights are advertised based on their luminosity, which ends up being what hobbyist gardeners use to evaluate their light source. Professional gardeners understand this difference, and will ignore measures of luminosity and instead focus on PAR, since that is actually rating what they care about.
Hope that helps!
TommyHobby
Active Member
gobbly, great post !! +rep
one thing is still unclear to me: For example - if I have lights that are 600 watt but only produce 50% of the 450 nm and 665 nm that the plants can use, and I have a 300 watt (theoretical) that produces 100% of the 450's and 665's that the plants can use - is that the same thing or is one better than the other although the lumens on the 300 watt light are alot less ?
one thing is still unclear to me: For example - if I have lights that are 600 watt but only produce 50% of the 450 nm and 665 nm that the plants can use, and I have a 300 watt (theoretical) that produces 100% of the 450's and 665's that the plants can use - is that the same thing or is one better than the other although the lumens on the 300 watt light are alot less ?
I am not nearly as versed in the biology behind photosynthesis. I basically trust that those botanists who developed the PAR spectrum knew what they were doing, so I'm not sure I can answer your question from a biology point of view. From a PAR point of view, it will peak at the two wavelengths, however, if you look at a PAR spectral graph (http://www.growfogbox.com/wp-content/uploads/2009/10/PAR_spectrum-300x169.jpg), it's a very broad range, so I'd suspect from a plant point of view a full spectrum with peaks around 450 and 665nm is going to be better than something with a more restricted spectrum.