Gavita DE vs. CMH 630w systems: pros and cons of both?

luxcultivars said:

Plenty of food for thought. Thanks for all the input. Obviously we all have preferences that we have biases towards. I am still leaning heavily towards the CMH. As far as initial investment costs go, I am willing to spend more, just not Greenbeams-level more. If I were rich I'd have wall to wall Greenbeams without a second thought.

That said, these Gavitas are being pushed really hard by the industry, and some people (bluerock included) are very convinced that they are better. I can see how they might be in a warehouse situation, but I'm a breeder with two 8 x 11 rooms.

It also honestly comes back to this point for me, which wasn't really addressed: if I can adequately light a 4' x 4' area with 630 watts, why would I go with a 1000w Gavita for that same space? Why bring in the extra heat and that famous hot spot? Assuming they both will be adequate light sources, of course.

IBogart, I've used light movers in the past. I gave mine away, never saw the point when compared to a room with wall to wall light coverage. But I'll read the link tonight. Thanks for the input.

Click to expand...

Gavita has a DE 600/750. Getting great reviews. That's probably gonna be my next light. For the money, there;s nothing sitting on the shelves that can beat it.


edit: Now that would be a fair test. A dual 315 fixture up against a gavita DE 600. If I only had the time and money, settle this once and for all.

iBogart said:

Beta Test Team said:

[FONT=Arial, Helvetica, sans-serif]I wrote that thread to which you refer, here:

[FONT=Arial, Helvetica, sans-serif]"LED vs. HPS: Truth about photosynthetic eff. & uniformity"
https://www.icmag.com/ic/showthread.php?t=296665[/FONT]

And this one is also based on that study, as well as other research by Bugbee & Nelson:

[FONT=Arial, Helvetica, sans-serif]"Gavita Pro DE vs. ePapillion: irradiance uniformity results"
https://www.icmag.com/ic/showthread.php?t=297147[/FONT][/FONT]

Click to expand...

[FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]
[/FONT][/FONT]Bravo! Atta boy beta.

What's your background man? Electrical engineer? Horticulture lighting business? Or just a hard on for the hobby?

Your stuff is in-depth man.

Click to expand...

Plant science (botany), with focus on photobiology, among other areas within the field of botany (all focusing on real-world application and plant growth).

iBogart said:

But back to that university study, it seems like the Gavita DE is king of the hill for cost of luminaire and umol output.

Click to expand...

The findings show ePapillion has about 1% greater umol/s output in PAR range than Gavita, and both ePapillion and Gavita have 1.7 umol in PAR range per watt exiting the aperture.

Now, I'm not saying ePapillion is better than Gavita, I think they're both very good for different use cases, but all in all, I think ePapillion is better simply for uniformity of radiation at canopy.

iBogart said:

The study also points out that quantity of umol frequency trumps quality of umol spectrum for plant photosynthesis which would seem to favor the DE HPS fixtures.

Click to expand...

That's something I pointed out in this thread, that it's PPF that's more important than spectra, and more important than PPF is DLI (which that study doesn't go into).

And that's my main point in this thread: if PPF at canopy is the same for Gavita and Double dPapillion (their 630W CMH luminaire), which is as simple as proper fixture numbers and placement, the better spectrum from the CMH is preferred as it means better plant growth and quality.

However, the issue of ROI, start-up costs, and operating costs come up in terms of commercial us of CMH, due to the relative greater cost per watt and the greater watts needed due to about 14% less photosynthetic effeincy of the Philips Greenpower CMH lamp (i.e. 1.91 umol/s per in PAR range per watt) and the Philps DE HPS used by Gavita and ePapillion (i.e. 2.1 umol/s in PAR range per watt).

So it's not black and white in terms of which is better, Gavita (or ePapillion) or 630W CMH (such as Double dPapillion), because if were only considering plant growth, quality, and yield, then CMH is better, but if we're also considering business considerations (like ROI, operating costs, and start-up costs), then it's a toss-up with a lead going to DE HPS.

If I were setting up a large commerical operatoin and money wasn't a major concern, I'd use CMH all day long, as Greenbeams lumainres, or at least Double dPapillion. The same for smaller canopies, like the 4'12' area I'm setting up this month using 6 Greenbeams (for a total of 1,890 watts) at 700-900 PPF at canopy.

iBogart said:

Another plus for the DE HPS, by this logic, is the high output of wavelengths in the 600 nm range, the range plants absorb the most for photosynthesis. Does this not hold true for you as well

Click to expand...

No, that does not hold true that 'red range' (600-700 nm) rich radiation is preferred for greatest photosynthetic rate.

The reason why, is it's best to consider all wavebands from 400-700 nm as providing the same photosynthetic rate, this is due to issues involving saturation of photosynthesis by various wavebands (e.g. later in the day green light often provides greater photosynthetic rate than red), how as leaves age they absorb differing wavebands for photosynthesis with varying efficiency (e.g. leaves lower on the plant do better with blue range than leaves near the top), how various wavebands affect stomatal opening and leaf tracking, etc.

Even the famous plant physiologist who is a author of that study, Dr. Bruce Bugbee, Ph.D. claims that same, that it's best to assume all wavebands within PAR range provide the same photosynthetic effect. This is also why quantum sensors do not 'weight' the wavebands when they're measured, they treat all wavelengths within PAR range as the same effect on photosynthesis.

The seminal study by Dr. Kieth McCree (ca. 1978), is what is used for the research showing 600-700 nm provides the most photosynthetic effect, however, it's very important to note his work was done with near-monochromatic lighting every 25 nm step-size (so, at 400 nm, 425 nm, 450 nm, and so on), it wasn't done under 'white light,' nor was every single nm studied, so the effects of all wavebands within PAR range at once wasn't taken into account, and the wavebands not used in his work were filled in with math (cubic spline interpolation). Therefore his work is a good approximation, but not hard fact.

So still the main reason DE HPS comes out on top in that study, which was about the economic issues of lighting, is that DE HPS is most efficient in turning watts into PAR range radiation, due mainly to its spectrum being so rich in red range photons, which require lower power input to create than blue and green range.

These two thread with our work may be of interest to you if you haven't read them yet:

"Various approximate RQE of Cannabis (graphed)"
https://www.icmag.com/ic/showthread.php?p=6718314

"Cannabis absorptance spectra: calculated and compared"
https://www.icmag.com/ic/showthread.php?t=293045

iBogart said:

as, if I read correctly in this thread, you favor the spectral output of the CMH 315?

Click to expand...

Most certainty, assuming ideal PPF is provided, which would be the same PPF provided if one was using 1000W DE HPS (e.g. Gavita, ePapillion, or Nanolux).

If sufficient PPF at canopy isn't provided, or too much PPF at canopy is provided, it doesn't matter what spectra is used (DE HPS, SE HPS, MH, or CMH), because plant growth, quality, and yield would suffer.

If SE MH and DE MH useful lifespan wasn't so short (max about 5,000 hours in the best case, normally more like 3,000-4,000), then a 1:1 mix of HPS and MH would be better than only using HPS, for the sake of better plant growth and quality.

Ideally at least about 13-15% of the PAR range radiation is from 400-500 nm. Which is why mixing HPS and MH is wise, if only MH has reasonable useful lifespan.

The issue of useful lifespan is very important when using many luminaires, simply due to the cost of re-lamping, in terms of keeping operating costs as low as possible.

iBogart said:

Gavita has a DE 600/750. Getting great reviews. That's probably gonna be my next light. For the money, there;s nothing sitting on the shelves that can beat it.


edit: Now that would be a fair test. A dual 315 fixture up against a gavita DE 600. If I only had the time and money, settle this once and for all.

Click to expand...

Hmm. I have strong doubts that a 600w Gavita (or a dialed-down-to-600w Gavita 1000w) would cut it the way 630 watts of CMH will. A 600w HPS definitely doesn't do a 4' x 4' area. Not to my satisfaction, anyway. You do love your Gavitas, though, don't you? I have a few months before the upgrades begin; I'll look further into them.

Love that dial-down feature. That's why I lean towards the DimLux version of 630CMH fixtures; multiple dial-down options. Last time I checked the Sun System ballast didn't have that.

Again: I'm specifically looking to fill a 4' x 4' footprint. 4 of them per room. Having more smaller fixtures is not a benefit to me.

I know; I keep obsessing over what I need. Sorry. The bottom line here is that a 1/3 reduction in electricity and a 1/3 reduction in heat times 8 lights (eventually) makes the CMH route a very tempting option.

iBogart said:

luxcultivars said:

[FONT=Arial, Helvetica, sans-serif]Plenty of food for thought. Thanks for all the input. Obviously we all have preferences that we have biases towards. I am still leaning heavily towards the CMH. As far as initial investment costs go, I am willing to spend more, just not Greenbeams-level more. If I were rich I'd have wall to wall Greenbeams without a second thought.

That said, these Gavitas are being pushed really hard by the industry, and some people (bluerock included) are very convinced that they are better. I can see how they might be in a warehouse situation, but I'm a breeder with two 8 x 11 rooms.

It also honestly comes back to this point for me, which wasn't really addressed: if I can adequately light a 4' x 4' area with 630 watts, why would I go with a 1000w Gavita for that same space? Why bring in the extra heat and that famous hot spot? Assuming they both will be adequate light sources, of course.

IBogart, I've used light movers in the past. I gave mine away, never saw the point when compared to a room with wall to wall light coverage. But I'll read the link tonight. Thanks for the input.[/FONT]

Click to expand...

Gavita has a DE 600/750. Getting great reviews. That's probably gonna be my next light. For the money, there;s nothing sitting on the shelves that can beat it.

edit: Now that would be a fair test. A dual 315 fixture up against a gavita DE 600. If I only had the time and money, settle this once and for all.

Click to expand...

In terms of a fair test when plant growth, quality, and yield are the important factors, try not to focus on the lamp wattage or lamp radiant PAR range umol/s, but instead on the PPF (irradiance) at canopy (and irradiance uniformity over all areas of the canopy), which is more a factor of how the luminaires are used, rather than the lamp's wattage or radiant PAR range umol/s.

I agree with lux about light movers. Better is to properly install fixtures (to have overlapping irradiance at canopy), and use ORCA film or a few coats of flat white paint on the walls and ceilig, with a few coats of flat white paint on the floor, to ensure high irradiance uniformity over all areas of the canopy (and greater radiation within the canopy, as well).

luxcultivars said:

Love that dial-down feature. That's why I lean towards the DimLux version of 630CMH fixtures; multiple dial-down options. Last time I checked the Sun System ballast didn't have that.

Click to expand...

I wasn't aware they made 630W CMH, thanks. For what it's worth, the Double dPapillion has dimming feature, as well.

luxcultivars said:

Again: I'm specifically looking to fill a 4' x 4' footprint. 4 of them per room. Having more smaller fixtures is not a benefit to me.

Click to expand...

Just to point out, using 8 315W fixtures, rather than 4 630W fixtures would provide better uniformity.

luxcultivars said:

Hmm. I have strong doubts that a 600w Gavita (or a dialed-down-to-600w Gavita 1000w) would cut it the way 630 watts of CMH will. A 600w HPS definitely doesn't do a 4' x 4' area. Not to my satisfaction, anyway. You do love your Gavitas, though, don't you? I have a few months before the upgrades begin; I'll look further into them.

Love that dial-down feature. That's why I lean towards the DimLux version of 630CMH fixtures; multiple dial-down options. Last time I checked the Sun System ballast didn't have that.

Again: I'm specifically looking to fill a 4' x 4' footprint. 4 of them per room. Having more smaller fixtures is not a benefit to me.

I know; I keep obsessing over what I need. Sorry. The bottom line here is that a 1/3 reduction in electricity and a 1/3 reduction in heat times 8 lights (eventually) makes the CMH route a very tempting option.

Click to expand...

That last part is why I'm going to try 630w of CDM as replacement for my current 1000w dual arc system. I went to the dual arc to get a more natural expression of the plants' potential & to encourage short internodes in my low overhead space. CDM is the next step in that.

I'm just an A64 compliant hobby grower who's gone to extraordinary lengths to create a grow space & to shed the heat in constructive ways. Check my albums. I'm not happy to be producing the heat in the first place, particularly in summer. We don't have refrigerated A/C but rather a large evaporative cooler & a whole house fan on the second floor, so the less heat created in the house the more comfortable it is. We also have plenty of fan noise already, so I'm looking forward to dialing down the grow space ventilation.

I try to be frugal about it, given that there's no monetary return, so I held out until I found a good deal on used ceramatec ballasts & plan on converting my current reflector to dual 315's when the current round finishes. I also get to use the less expensive T9 lamps because it's an enclosed luminaire. I figure savings on electricity will put me at the break even point in less than 2 years & that longer lamp life will make that even better.

The DE's may well be a better solution for commercial growers of any size at all given lower up front costs & simpler management of (maybe) fewer fixtures. Whether they'll actually grow better than the same wattage of CDM is another question entirely.

When I think about it at all, I wonder how good all the scientific measurements of light intensity really are, the simple counting of photons. Given that the plants capture photons for their energy, I wonder if they get higher utility from higher energy blue photons. If they do, then the proportions of different wavelengths would need to be weighted to reflect that.

Jhhnn said:

When I think about it at all, I wonder how good all the scientific measurements of light intensity really are, the simple counting of photons. Given that the plants capture photons for their energy

Click to expand...

There has been a ton of research into the topic of whether quantum sensor should use a flat (unweighted) measures of wavebands in PAR range, or weight the wavebands according to how plants' use them for various action spectra. And there are two reasons why it's been agreed for decades that the basic measure of irradiance for plant growth should be unweighted quanta (photons), rather than weighted:

(1) As I wrote on the last page, in terms of the most important action spectra, photosynthesis by wavelength, it's best to assume all wavelengths provide the same effect on photosynthesis, therefore flat measurement is preferred.

(2) There are no quantum sensor filters good enough to mimic the action spectrum of photosynthesis (unlike the fliters used to mimic how human eyes use PAR range light, for lux meters), and creating such filters would be very costly. There are however, fairly inaccurate "YPF" (yield photon flux) sensors, which are quantum sensor that weight wavebands. So if a scientist wants accurate YPF measurements of PAR range radiation, i.e. measure irradiance and weight it for effect on photosynthesis, a spectroradiometer is used along with RQE of photosynthesis (a spectroradiometer measures single wavelengths or wavebands, with single wavelength measurements being far preferred for accuracy).

To learn more about action spectra and RQE's, see the work we've done in links in my signature.

A useful value is the YPF/PPF ratio for various lamps. That is useful because the ratio is created with a spectroradiometer, and then with a good quantum sensor one only has to measure PPF to find YPF. That is, if the PPF at canopy is 500, and the YPF/PPF ratio is 0.898, the YPF at canopy is 449.

Worth noting is DE HPS YPF/PPF value is about 0.97, while YPF/PPF value for the most effecient CMH is 0.898, which is about 8.6% less for the CMH than the DE HPS, which isn't too shabby.

To see YPF/PPF values for various lamps, including Philips Greenpower 315W CMH (i.e. 0.898) and Philips MasterColor Elite 942 CMH (i.e. 0.892), see this work by Nelson & Bugbee:

"Spectral characteristics of lamp types for plant biology"
http://www.researchgate.net/publica...aracteristics_of_lamp_types_for_plant_biology

And to see YPF/PPF data for DE HPS, along with other data about DE HPS vs. SE (mogual base) HPS, see this work by Nelson & Bugbee:

"Advances in HPS technology: electronic ballasts, efficient luminaires, and double-end"
http://www.researchgate.net/publica...s_efficient_luminaires_and_double-ended_lamps

The same type of ratio can be crated for any action spectra that one knows the RQE of, using a spectroradiometer to create an SPD of the lamp. The spreadsheet we've been working on, "HISSA," does that in an automated fashion, however, until I can afford to get many lamps analyzed with a spectroradiometer our work on HISSA has stalled, because the SPD published by lamp manufacturers isn't good to digitize due to errors in the digitization processes, and lack of measure of wavelengths below 400 nm and above 700 nm.

Jhhnn said:

I wonder if they get higher utility from higher energy blue photons. If they do, then the proportions of different wavelengths would need to be weighted to reflect that.

Click to expand...

In terms of action spectrum of photosynthesis, it's about 600 to 620 nm that provides that greatest effect on photosynthesis, not blue range.

But, blue range is the most effective range for other action spectra than photosynthesis, so in that case weighting would use blue as the most efficient (depending upon the action spectrum under discussion). See links in my signature, especially the second one.

Beta Test Team said:

I wasn't aware they made 630W CMH, thanks. For what it's worth, the Double dPapillion has dimming feature, as well.


Just to point out, using 8 315W fixtures, rather than 4 630W fixtures would provide better uniformity.

Click to expand...

Yeah, the 630 DimLux looks pretty nice. I've seen it listed for about $700. I also fancy their total-system controller. Strangely though, the DimLux web site no longer lists it. Plenty of suppliers, most of them in Europe. A few in the states. I emailed them to see if it's discontinued. I could go for the double DPap instead I guess.

http://www.urbnag.com/products/dimlux-expert-series-630w-dual-full-spectrum/

I agree about smaller vs larger fixtures. It's the cost difference that stops me. 4 x $700 vs. 8 x ~$500. Times two rooms and that's a $2,400 difference. Maybe things will get cheaper in the next 3 months before I buy, but I doubt it.

Oh, thanks for the link. Now I see it I do recall learning about it rives's thread. The thing about that reflector I don't like is it's specular, not diffuse reflective surface.

Beta Test Team said:

There has been a ton of research into the topic of whether quantum sensor should use a flat (unweighted) measures of wavebands in PAR range, or weight the wavebands according to how plants' use them for various action spectra. And there are two reasons why it's been agreed for decades that the basic measure of irradiance for plant growth should be unweighted quanta (photons), rather than weighted:

(1) As I wrote on the last page, in terms of the most important action spectra, photosynthesis by wavelength, it's best to assume all wavelengths provide the same effect on photosynthesis, therefore flat measurement is preferred.

(2) There are no quantum sensor filters good enough to mimic the action spectrum of photosynthesis (unlike the fliters used to mimic how human eyes use PAR range light, for lux meters), and creating such filters would be very costly. There are however, fairly inaccurate "YPF" (yield photon flux) sensors, which are quantum sensor that weight wavebands. So if a scientist wants accurate YPF measurements of PAR range radiation, i.e. measure irradiance and weight it for effect on photosynthesis, a spectroradiometer is used along with RQE of photosynthesis (a spectroradiometer measures single wavelengths or wavebands, with single wavelength measurements being far preferred for accuracy).

To learn more about action spectra and RQE's, see the work we've done in links in my signature.

A useful value is the YPF/PPF ratio for various lamps. That is useful because the ratio is created with a spectroradiometer, and then with a good quantum sensor one only has to measure PPF to find YPF. That is, if the PPF at canopy is 500, and the YPF/PPF ratio is 0.898, the YPF at canopy is 449.

Worth noting is DE HPS YPF/PPF value is about 0.97, while YPF/PPF value for the most effecient CMH is 0.898, which is about 8.6% less for the CMH than the DE HPS, which isn't too shabby.

To see YPF/PPF values for various lamps, including Philips Greenpower 315W CMH (i.e. 0.898) and Philips MasterColor Elite 942 CMH (i.e. 0.892), see this work by Nelson & Bugbee:

"Spectral characteristics of lamp types for plant biology"
http://www.researchgate.net/publica...aracteristics_of_lamp_types_for_plant_biology

And to see YPF/PPF data for DE HPS, along with other data about DE HPS vs. SE (mogual base) HPS, see this work by Nelson & Bugbee:

"Advances in HPS technology: electronic ballasts, efficient luminaires, and double-end"
http://www.researchgate.net/publica...s_efficient_luminaires_and_double-ended_lamps

The same type of ratio can be crated for any action spectra that one knows the RQE of, using a spectroradiometer to create an SPD of the lamp. The spreadsheet we've been working on, "HISSA," does that in an automated fashion, however, until I can afford to get many lamps analyzed with a spectroradiometer our work on HISSA has stalled, because the SPD published by lamp manufacturers isn't good to digitize due to errors in the digitization processes, and lack of measure of wavelengths below 400 nm and above 700 nm.


In terms of action spectrum of photosynthesis, it's about 600 to 620 nm that provides that greatest effect on photosynthesis, not blue range.

But, blue range is the most effective range for other action spectra than photosynthesis, so in that case weighting would use blue as the most efficient (depending upon the action spectrum under discussion). See links in my signature, especially the second one.

Click to expand...

Meh. If we were to design the perfect grow lamp, its output would basically conform to the familiar double humped absorption curve we all know. That's how the plant absorbs light when it has all the power it could want from natural sunlight. That's how it optimizes all the organic processes at work. It's the result of a billion years of evolution.

When we look at the spectral output graph of any HPS lamp, DE's included, there's basically no blue, so the plants have to use less than optimal means to use the light they can get for the same purposes they'd normally use blue light.

Only plants' ability to adapt to unnatural lighting allows them to grow under HPS at all, a situation that's stressful by definition. They're constantly compensating for the lack of blue light.

That's not a problem with dual arc & CDM lamps, the latter being more efficient in terms of power consumption.

Jhhnn said:

Meh. If we were to design the perfect grow lamp, its output would basically conform to the familiar double humped absorption curve we all know. That's how the plant absorbs light when it has all the power it could want from natural sunlight. That's how it optimizes all the organic processes at work. It's the result of a billion years of evolution.

Click to expand...

Meh? Really? Not sure why you always seem to poo-poo the science I provide, considering our work is far better and more correct than past claims about Cannabis usage of radiation claimed by growers over the past 3 or 4 decades (with the exception of knna, however, his work was limited in scope compared to ours). Our work is based upon plant science, other claims are based upon flawed and incomplete understating of science and use of conjecture.

The double hump curve to which I assume you refer is not what a perfect grow lamp spectrum would be, because that double hump is simply chlorophyll A & B absorption spectra. And that is not how Cannabis nor other plants absorb radiation (there's a lot more going on than just Chl A & B).

If we were to design a lamp spectrum to match Cannabis absorpance (the same thing as absorbed radiation), it would look like this (from the 1st link in my signature):



However, I'm not saying that's an ideal spectrum for lamps used to grow plants in controlled environments, but it is the best approximation of how Cannabis absorbs radiation from veg to harvest.

Jhhnn said:

When we look at the spectral output graph of any HPS lamp, DE's included, there's basically no blue, so the plants have to use less than optimal means to use the light they can get for the same purposes they'd normally use blue light.

Click to expand...

That's not wholly correct, while it's true for photosynthesis, it's not true for many other photobiological reactions. A plant can't use red photons in lue of blue photons for various photobiological reactions that require blue photons, such as phototropism or especially cryptochrome mediated responses. And the same goes for blue photons in lue red and far red photons, for example, for phytochrome mediated responses (like photoperiodism).

And it's DE HPS that has the lowest % blue range (around 2-3%), many mogul base HPS have enough blue light (around 4-5%, not ideal, but enough), and options such such as Hortilux Super HPS have even more blue range (around 5-7%).

An ideal goal for % blue range light is ~15%, with a range from ~10% to ~15% (no more than ~20%). This is due to various reasons, such as elongation, and one of the most important for indoor plant growth is lamp efficiency, because it takes more power to produce blue range photons (because they're quite energetically expensive) than green and red range photons.

Look at the second link in my signature to see the effect of blue light on plants in terms of the most important action spectra.

Here are two studies you may like to review:

"Photobiological Interactions of Blue Light and Photosynthetic Photon Flux: Effects of Monochromatic and Broad-Spectrum Light Sources"
http://www.researchgate.net/publica...onochromatic_and_Broad-Spectrum_Light_Sources

"Spectral Effects of Three Types of White Light-emitting Diodes on Plant Growth and Development:Absolute versus Relative Amounts of Blue Light"
http://cpl.usu.edu/files/publications/publication/pub__4124704.pdf

Jhhnn said:

Only plants' ability to adapt to unnatural lighting allows them to grow under HPS at all, a situation that's stressful by definition. They're constantly compensating for the lack of blue light.

Click to expand...

Photoadpatoin only goes so far, and Cannabis grows okay under red light (600-700 nm), albeit growth is much better under white light, due to the strong effect blue light (400-500 nm) and green light (500-600 nm) have on many photobiological reactions. Again, see the second link in my sig, this one:

"Various approximate RQE of Cannabis (graphed)"
https://www.icmag.com/ic/showthread.php?p=6718314

See the study I posted on the first page looking at effect of various wavebands (blue, green, and red) on Cannabis growth and cannabinoid production.

Greenbeams vs. 1,000 watt hps

Greenbeams vs. 1,000 watt hps

This may have been posted before, but I haven't seen it. See the attached document where Greenbeams were compared to 1,000 watt hps lights in a Colorado grow op. If it's a valid comparison then the Greenbeams are a slam dunk. I'm not so sure how the GB's would fare in a comparison with Gavitas or Epaps.

Hey timmur,

I'm the one that consulted Cycloptics and the grower on that grow test, to setup and use the Greenbeams fixtures (e.g. in terms of goal PPF, room setup, etc.), and I also hung much of the ORCA on those walls in the pictures . The funny thing is the grower didn't use the GB correctly to plan, and had they, the results would have been even better.

Greenbeams would also beat Gavita or ePapillion, assuming ideal PPF at canopy was used for all rooms, simply due to the better spectrum from the Philips CMH and uniformity of PPF at canopy from Greenbeams. In these cases, penetration isn't an issue due to the many fixtures per room.

The only downside about Greenabeams, or any 315w system as luxcultivar pointed out, is the start-up cost.

Only plants' ability to adapt to unnatural lighting allows them to grow under HPS at all, a situation that's stressful by definition. They're constantly compensating for the lack of blue light.

Click to expand...

This sounds like pure speculation, not science. How do you figure that they are 'compensating'? I'm seeing explosive flowering and growth, not compensation.

It is also a lot more complicated than 'they need more blue'. I think BTT was trying to show you that. Reducing things to their simplest form isn't always the best approach. In this case too much detail is lost in that translation.

When it comes to measuring actual plant performance and achieving the true genetic potential of various hybrids and strains (something I strive towards and usually achieve), your 'more blue' theory doesn't hold up. For example, I have grown and flowered cannabis several times under conventional metal halides with plenty of blue (6500k), and also under Eye-Hortilux HPS. The HPS definitely brings in the higher yields with ease. Quality seems superior as well, subjective as that is. Why would this be so if your theory is even vaguely correct?

I'm not anti-blue so much as of the mind that designing lights that specifically output only the spectrums that plants actually use - be that warm or cool or preferably some of both - rather than wasting electricity generating photons that have no use to the plant. That is just extra heat.

This is what got me leaning towards the CMH, actually; the targeted horticultural spectrum.

Very cool! Like I said, if it's true then they are a slam dunk! It sounds like you're saying that comparison is legit (even though they strayed from the plan). Let's do the math: 1.2 months payback on a commercial grow = amazing ROI. People who complain about the cost are probably not aware of the ROI or are doing hobby grows where the extra cost might not be worth it.

Beta Test Team said:

Hey timmur,

I'm the one that consulted Cycloptics and the grower on that grow test, to setup and use the Greenbeams fixtures (e.g. in terms of goal PPF, room setup, etc.), and I also hung much of the ORCA on those walls in the pictures . The funny thing is the grower didn't use the GB correctly to plan, and had they, the results would have been even better.

Greenbeams would also beat Gavita or ePapillion, assuming ideal PPF was used for all rooms, simply due to the better spectrum from the Philips CMH.

The only downside about Greenabeams, or any 315w system as luxcultivar pointed out, is the start-up cost.

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timmur said:

Beta Test Team said:

timmur said:

This may have been posted before, but I haven't seen it. See the attached document where Greenbeams were compared to 1,000 watt hps lights in a Colorado grow op. If it's a valid comparison then the Greenbeams are a slam dunk. I'm not so sure how the GB's would fare in a comparison with Gavitas or Epaps.

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Hey timmur,

I'm the one that consulted Cycloptics and the grower on that grow test, to setup and use the Greenbeams fixtures (e.g. in terms of goal PPF, room setup, etc.), and I also hung much of the ORCA on those walls in the pictures . The funny thing is the grower didn't use the GB correctly to plan, and had they, the results would have been even better.

Greenbeams would also beat Gavita or ePapillion, assuming ideal PPF was used for all rooms, simply due to the better spectrum from the Philips CMH.

The only downside about Greenabeams, or any 315w system as luxcultivar pointed out, is the start-up cost.

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Very cool! Like I said, if it's true then they are a slam dunk! It sounds like you're saying that comparison is legit (even though they strayed from the plan). Let's do the math: 1.2 months payback on a commercial grow = amazing ROI. People who complain about the cost are probably not aware of the ROI or are doing hobby grows where the extra cost might not be worth it.

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Yup, the results are true and comparison is legit.

The ROI issue is very true, as well. I've done math for very large facilities (with more than 2,000 Greenbeams), and just from the extra yield the extra start-up costs are paid for within two years. ROI annualized over a few years is really great. The only point I was making a few pages back, was ROI compared to e.g. Gavita takes longer to get into black due to greater start-up cost of Greenbeams to provide the same PPF at canopy.

For example, setting up 30K sq. ft. canopy area with Gavita or ePapillion may be around $150,000 to $300,000 (depending upon price per unit and number of units), but the same area for Greenbeams is around $750,000 to $1,000,000+ (depending upon price per unit and number of units).

luxcultivars said:

This sounds like pure speculation, not science. How do you figure that they are 'compensating'? I'm seeing explosive flowering and growth, not compensation.

It is also a lot more complicated than 'they need more blue'. I think BTT was trying to show you that. Reducing things to their simplest form isn't always the best approach. In this case too much detail is lost in that translation.

When it comes to measuring actual plant performance and achieving the true genetic potential of various hybrids and strains (something I strive towards and usually achieve), your 'more blue' theory doesn't hold up. For example, I have grown and flowered cannabis several times under conventional metal halides with plenty of blue (6500k), and also under Eye-Hortilux HPS. The HPS definitely brings in the higher yields with ease. Quality seems superior as well, subjective as that is. Why would this be so if your theory is even vaguely correct?

I'm not anti-blue so much as of the mind that designing lights that specifically output only the spectrums that plants actually use - be that warm or cool or preferably some of both - rather than wasting electricity generating photons that have no use to the plant. That is just extra heat.

This is what got me leaning towards the CMH, actually; the targeted horticultural spectrum.

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The reason you see the results you do is because the plants are better at adapting to a lack of blue than to a lack of red. Beta's links bear that out, as well. Prior to CMH & now CDM, it was not possible to have both in one lamp other than w/ dual elements.

Hey BTT, exactly how high up were those Greenbeams from the canopy? They look like they are up about 8'... that seems excessive.

In an 18' x 18' room that's what - 6 lights per 18 foot side? Approximately 1 fixture per 3 foot area. So that sort of height has me wondering how there was enough light. Sorry if I missed that somewhere. Maybe it was a 30" area, to allow for movement.

Again, that steeeep fixture cost at the 315w level always floors me. I start thinking "why not just get double fixtures for ~$700, those hung over a 4' x 4' area?" I don't see how the reduced output from a double fixture could make that not a very viable way to cut initial investment costs.

I'm dying to see some comparative tests like these using the double-bulb CMH fixtures. Stack a 630W up against a 1000w Eye-Horti HPS with equal footprints and I wonder how they'd shape up.

Jhhnn said:

The reason you see the results you do is because the plants are better at adapting to a lack of blue than to a lack of red. Beta's links bear that out, as well. Prior to CMH & now CDM, it was not possible to have both in one lamp other than w/ dual elements.

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My point was this: if you can't see the difference on the scale at the end, how are you quantifying the fact that the plant is worse off and 'compensating'?

Anyway, I think we're all on the same page in wanting more usable spectrum from our wattage inputs. Thanks for the input.

Beta Test Team said:

Meh? Really? Not sure why you always seem to poo-poo the science I provide, considering our work is far better and more correct than past claims about Cannabis usage of radiation claimed by growers over the past 3 or 4 decades (with the exception of knna, however, his work was limited in scope compared to ours). Our work is based upon plant science, other claims are based upon flawed and incomplete understating of science and use of conjecture.

The double hump curve to which I assume you refer is not what a perfect grow lamp spectrum would be, because that double hump is simply chlorophyll A & B absorption spectra. And that is not how Cannabis nor other plants absorb radiation (there's a lot more going on than just Chl A & B).

If we were to design a lamp spectrum to match Cannabis absorpance (the same thing as absorbed radiation), it would look like this (from the 1st link in my signature):

View Image

However, I'm not saying that's an ideal spectrum for lamps used to grow plants in controlled environments, but it is the best approximation of how Cannabis absorbs radiation from veg to harvest.


That's not wholly correct, while it's true for photosynthesis, it's not true for many other photobiological reactions. A plant can't use red photons in lue of blue photons for various photobiological reactions that require blue photons, such as phototropism or especially cryptochrome mediated responses. And the same goes for blue photons in lue red and far red photons, for example, for phytochrome mediated responses (like photoperiodism).

And it's DE HPS that has the lowest % blue range (around 2-3%), many mogul base HPS have enough blue light (around 4-5%, not ideal, but enough), and options such such as Hortilux Super HPS have even more blue range (around 5-7%).

An ideal goal for % blue range light is ~15%, with a range from ~10% to ~15% (no more than ~20%). This is due to various reasons, such as elongation, and one of the most important for indoor plant growth is lamp efficiency, because it takes more power to produce blue range photons (because they're quite energetically expensive) than green and red range photons.

Look at the second link in my signature to see the effect of blue light on plants in terms of the most important action spectra.

Here are two studies you may like to review:

"Photobiological Interactions of Blue Light and Photosynthetic Photon Flux: Effects of Monochromatic and Broad-Spectrum Light Sources"
http://www.researchgate.net/publica...onochromatic_and_Broad-Spectrum_Light_Sources

"Spectral Effects of Three Types of White Light-emitting Diodes on Plant Growth and Development:Absolute versus Relative Amounts of Blue Light"
http://cpl.usu.edu/files/publications/publication/pub__4124704.pdf


Photoadpatoin only goes so far, and Cannabis grows okay under red light (600-700 nm), albeit growth is much better under white light, due to the strong effect blue light (400-500 nm) and green light (500-600 nm) have on many photobiological reactions. Again, see the second link in my sig, this one:

"Various approximate RQE of Cannabis (graphed)"
https://www.icmag.com/ic/showthread.php?p=6718314

See the study I posted on the first page looking at effect of various wavebands (blue, green, and red) on Cannabis growth and cannabinoid production.

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I think we're fundamentally saying the same thing, just in different ways. I'm more interested in the fundamental aspects while you deal with scientific study of the details.

My contention is simply that the closer we get to natural sunlight at sufficient intensities the less the rest of it matters to growers rather than scientists.

I referenced the photosynthesis curve with the understanding that photosynthesis is the prime life process utilizing most of the energy derived from light. Obviously, plants use light for other processes but those curves fall well below that of photosynthesis. Of all the light the plant uses, it devotes the vast majority to photosynthesis. If a lamp produced that kind of output, there's plenty of light at all the optimal frequencies for those lesser processes.

That's if you want to optimize efficiency. Short of that, the realm of reality, is that the closer to natural sunlight the better simply because the plants receive a more balanced light diet. CDM does that far better than anything else.

My perspective isn't that of a warehouse grower but rather a home grower. For those of us in that position, CDM makes a lot of sense provided we're willing to bear the upfront costs. For the amount of useable light, they're more efficient & run cooler, a boon for both air cooling & refrigerated cooling. Strong blue spectrum encourages short internodes & bushy growth, never a bad thing with average to short ceiling height. They also provide the most balanced light diet and thus the most natural results in terms of aroma, flavor & effect.