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

luxcultivars said:

BTT has no vested interest in CMH. That's a serious stretch.

You seem to be missing my point. If a 630w double-bulb CMH achieves (weight and quality-wise) what a 1000w Gavita does (as claimed by some in the 315w CMH thread), the Gavita is not a 'better' or more efficient fixture. It consumes ~30% more electricity, generates ~1/3 more heat. To be correct with that assessment you'd need to be pulling in 1/3 more weight than a person with a 630w CMH, and... I seriously doubt that is happening. This is assuming quality is a given with a dialed-in feeding regimen.

Understand that I don't have any CHM fixtures. yet. I am re-designing my entire scene and the 630w CMH potentially looks like a great option (aside from the steep initial investment). I am open to other types like the Gavitas, but the feedback that I am getting from friends in the field is that they are overhyped and overrated. So here I am investigating it further.

As far as lower bud development goes, I think you are possibly a bit confused about how plants actually process energy via photosynthesis and distribute it to the entire plant rather than just the tops which are exposed to the most light. A few years ago on another forum this was discussed in detail and a side by side was done where the lower buds were actually screened from direct light on half of a plant... and they developed just as well as the buds that weren't screened. The only difference was that they were slightly lighter green. Density was the same.

I realize that this is anecdotal, but that result matches what I have seen over 20 years of growing. Some strains are definitely prone to looser lower buds, but it has little to do with the actual light intensity down there provided the plant itself is being hit with full intensity at the canopy top.

I find it highly unlikely that a CMH would have such an insufficient penetration that it would measurably negatively affect lower flower development.

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Firstly, I simply asked if Beta had a vested interest. That's not an unfair question in my eyes considering the content of his many prior posts.

With the CMH as described, you don't have a 630w fixture, you have a fixture with two 315w bulbs. That greatly affects output intensity vs. an actual 630w bulb.

As far as lower flower development goes, I am not at all confused as to how photosynthesis works. You are correct that flowers will develop seemingly fine in shaded conditions. However, it has been my experience that those same flowers - subjected to more direct light - are superior in all respects to their shaded brethren. The miniature chemical factories knows as resin glands alter their chemical reactions based on light received. That is personal experience, no science to back it. Nonetheless, commercial growers routinely prune their tightly packed plants in an effort to get more light down to these lower flowers. They claim better yield and a more uniform finished product from these efforts. That is my finding as well.

which non vented/winged reflector pairs the best with the 315w bulbs?

@rives retro fitted a bell 600 and documented the bulb being pretty centered. wonder what other hoods (non pre packaged) people are finding to work well throwing these "smaller" hid's

bluerock said:

Firstly, I simply asked if Beta had a vested interest. That's not an unfair question in my eyes considering the content of his many prior posts.

With the CMH as described, you don't have a 630w fixture, you have a fixture with two 315w bulbs. That greatly affects output intensity vs. an actual 630w bulb.

As far as lower flower development goes, I am not at all confused as to how photosynthesis works. You are correct that flowers will develop seemingly fine in shaded conditions. However, it has been my experience that those same flowers - subjected to more direct light - are superior in all respects to their shaded brethren. The miniature chemical factories knows as resin glands alter their chemical reactions based on light received. That is personal experience, no science to back it. Nonetheless, commercial growers routinely prune their tightly packed plants in an effort to get more light down to these lower flowers. They claim better yield and a more uniform finished product from these efforts. That is my finding as well.

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Fair enough. I appreciate the input. Glad to see things staying civil. Too many ruined threads; just hoping to avoid digression.

Anyway, IME pruning away fans to get stronger light to the lowers mainly just makes them a darker green, and has a minimal effect on total density and yield. I do it all the time. I agree to disagree on the overall significance of that. I think it is likely fairly strain-dependent. I never see any larfy lower flowers but I'm admittedly using Eye-Hortis right now.

As far as the 315w single vs. the 630w double, well, yeah. I'm not going to spend the extra cash on two 315s when I can use a double-bulb fixture like the DimLux or Sun System. The main downside of a bit of light loss will be... that I have to lower the fixture a bit more? That doesn't bother me much. Everyone's mileage will vary there. I would love to buy eight Greenbeams. The cost difference is $2800 for four DimLux 630s or $4,800 for eight Greenbeams and bulbs. Not a tough choice there. The Sun System 315s are better at ~$450 each, but I still lean towards the 630 fixtures.

Everything I read in various forums says that personal results show these 630s to be fairly close to a 1000 HPS in terms of yields and quality and footprint. I am going by other people's experiences here. BTT obviously knows the specifics more than I do.

I would also like to mention that I have made a serious effort over the last two years to stop spending so much energy chasing that '5% better' dragon. As you know, if any given light fixture reaches a certain point of effectiveness, more output beyond that isn't necessarily better. If I can light a 48" x 48" area with a double CMH and maintain my current output and quality, I'd do that over the Gavita for obvious reasons. If I can't... well, here I am. That's why I'm asking.

I admit a lack of personal knowledge/experience about the CMH, so all with a grain of salt. I do like what I have heard, though. All I ever seem to hear from Gavita buyers I know is 'hot spot'. I can see Gavitas as probably being preferable in a warehouse situation. But in an 8' x 8' breeding room?

bluerock said:

So you are stating that as long as the PPF at canopy is equal, the light output beyond that range is, in fact, linear regardless of wattage or varying lumen output of different bulb types?

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What I'm stating is if the PPF is the same at a higher plane, then the PPF will be similar at a lower plane, for point source radiatoin (so, a single fixture, for example), even if one luminaire is a 1,000W and the other 630W.

But if it's the same lamp and same wattage, like we're discussing in terms of Gavita vs. ePapillion in this thread, then if the higher plane PPF is the same, the lower plane PPF will be the very close to the same (again, as a point source,so as single fixture).

However, when we're talking about multiple fixtures in an area, like how large grows should be setup, where there's overlapping radiation between fixtures with the same lamp, point source radiation isn't happening, so lower planes of PPF will be quite similar regardless of lamp wattage. So e.g., two exactly same rooms (not taking wall reflection into account), one with 1000W DE HPS fixtures, and the other with 630W CMH fixtures (two 315W CMH in a single fixture), if the higher plane PPF is the same, the lower plane PPF will be very close to the same.

As a real work example, I just took two sets of PAR range micromole measurements using a SunSystem II reflector, Phantom digital ballast, and Hortilux Super HPS 600W, along with my LI-COR quantum sensor (allowing ~20 minutes warm up time for each power setting).

The first readings were at 100% power (so, 600W), the second readings were at 60% power (so, 360W). The higher plane readings were both at about 1,680 umol/s/quarter inch squared, the lower plane readings were both at 1' below the higher plane.

This testing is to show the effect of lamp wattage (and so, radiance) on 'penetration,' that is, effect on irradiance as the measurements get further from the higher plane.

The following test isn't rigors by any means, but it is accurate enough for this example. I eyeballed he distance measurements with a tape measure, for example, and eyeballed holding the sensor directly below the center of the lamp, while doing my best to ensure the sensor was level with my leveling holder for the sensor.

What the following testing shows is there isn't a great effect on 'penetration' due to lamp wattage, which in this case was about 14% greater irradiance at 1' penetration for the 600W setting vs. the 360W setting. I.e. at 40% less power from the lamp, the irradiance was only ~14% less at the lower plane. Which translates to 80 more micromole per second per area for the 600W setting at the lower plane, and that 80 umol isn't considerable in terms of effects on growth.

Note that this testing is for point source radiation, i.e. a single fixture, whereas if I had multiple fixtures setup in the room the lower plane irradiance values would be considerably closer to the same for each lamp type.

600W setting:
~1,680 umol per second per 1/4" squared @ ~11" from glass
~580 umol per second per 1/4" squared @ ~23"' from glass

360W setting:
~1,680 umol per second per 1/4" squared @ ~5.5"' from glass
~500 umol per second per 1/4" squared @ ~17.5" from glass

That area of 1/4" squared is the area of the sensor lens. So to find true PPF many measurements would be taken within a 3'x3' area and averaged, for indoor growth rooms, due to the non-uniform nature of radiation indoors. But for outside under the sun, only one measurement needs to be taken to find PPF, because the sun's radiation is so uniform over any 3'x3' area.

About that testing I did in the post above, the two tested lamp wattage were 600W and 360W, so the lower wattage was 60% of the higher wattage. And in terms of 1000W DE HPS vs. 630W CMH, the lower wattage (CMH) is 63% of the higher wattage.

That's as close as I could get at this time to the thread topic in terms of testing today from single fixtures. And I think that's not too bad, 60% vs. 63%, in terms of getting an idea of effect of penetration by different wattage lamps.

Beta: Please refer to the title of this thread. As you have previously stated, staying on topic is a subject near and dear to your heart. I didn't say "similar", I said "linear". Both your equipment and measurements have nothing whatever to with the thread topic. How in the hell does a Phantom ballast setup w/ Hortilux SE figure into the equation? It doesn't.

Gavita vs. Epap? Are you referring to comparable DE equipment? Or does Phillips refer to their CMH offering as "Epaps"? Again, thread title, are you on topic?

Lux: I can't cite the source, but some Hollywood/Broadway type once pointed out: "from the fires of derision, flows molten excellence". Indeed.

bluerock said:

Beta: Please refer to the title of this thread. As you have previously stated, staying on topic is a subject near and dear to your heart.

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I haven't gone off topic.

Lux was asking about 1000W DE HPS (as Gavita) vs. 630W CMH, which I have posted about (regarding spectra differences, etc., see the first page). And billyboat mentioned Gavita vs. ePapillion vs. Nanolux, in terms of penetration and yield, to which you commented that Gavita is the best, where we all were discussing penetration. You also commented that Gavita is way better (paraphrasing) than 630W CMH, e.g. in terms of penetration due to lamp wattage, to which I disagreed. And Lux took issue with your comparison of CMH to T5's while you claimed CMH won't grow large lower flowers.

Part of this thread has been about the issue of penetration, something the OP (Lux) has also commented on.

bluerock said:

I didn't say "similar", I said "linear". Both your equipment and measurements have nothing whatever to with the thread topic. How in the hell does a Phantom ballast setup w/ Hortilux SE figure into the equation? It doesn't.

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I didn't agree with your question about linear, no need to get huffy.

What my testing showed, and I thought you would have been appreciative, by the way, is the issue of penetration as it relates to lamp wattage, something you (and others) have been posting about in this thread...

The difference in wattage between 1000W DE HPS and 630W CMH is 63%, the difference in wattage in my testing was 60%. Those two values are pretty close, so my testing gives data regarding the issue of penetration differences between 1000W and 630W.

You were the loudest person in this thread in regards to penetration as it relates to lamp wattage...

bluerock said:

Gavita vs. Epap? Are you referring to comparable DE equipment? Or does Phillips refer to their CMH offering as "Epaps"? Again, thread title, are you on topic?

Click to expand...

See what I wrote above, about billyboat's post, my posts, your posts and Lux's posts.

I don't see why you're getting so upset, but I do agree with Lux's point that you seem to be getting hostile.

I think maybe because we're not all agreeing with you that Gavita 1000W DE HPS luminaire is god's gift (again, paragraphing), and I showed how your claims about penetration as it relates to wattage aren't correct, you're getting upset. I'm not trying to upset you, I'm simply trying to post provable facts.

I'll bow out of this thread for now, goodnight.

Beta Test Team said:

I haven't gone off topic.

Lux was asking about 1000W DE HPS (as Gavita) vs. 630W CMH, which I have posted about (regarding spectra differences, etc., see the first page). And billyboat mentioned Gavita vs. ePapillion vs. Nanolux, in terms of penetration and yield, to which you commented that Gavita is the best, where we all were discussing penetration. You also commented that Gavita is way better (paraphrasing) than 630W CMH, e.g. in terms of penetration due to lamp wattage, to which I disagreed. And Lux took issue with your comparison of CMH to T5's while you claimed CMH won't grow large lower flowers.

Part of this thread has been about the issue of penetration, something the OP (Lux) has also commented on.


I didn't agree with your question about linear, no need to get huffy.

What my testing showed, and I thought you would have been appreciative, by the way, is the issue of penetration as it relates to lamp wattage, something you (and others) have been posting about in this thread...

The difference in wattage between 1000W DE HPS and 630W CMH is 63%, the difference in wattage in my testing was 60%. Those two values are pretty close, so my testing gives data regarding the issue of penetration differences between 1000W and 630W.

You were the loudest person in this thread in regards to penetration as it relates to lamp wattage...


See what I wrote above, about billyboat's post, my posts, your posts and Lux's posts.

I don't see why you're getting so upset, but I do agree with Lux's point that you seem to be getting hostile.

I think maybe because we're not all agreeing with you that Gavita 1000W DE HPS luminaire is god's gift (again, paragraphing), and I showed how your claims about penetration as it relates to wattage aren't correct, you're getting upset. I'm not trying to upset you, I'm simply trying to post provable facts.

I'll bow out of this thread for now, goodnight.

Click to expand...

Hostile? Ridiculous. You have gone into what I consider "propaganda mode" and are attempting to misquote me. An often subtle thing, but I do not tolerate it. Why would I? I'll skip the subtle stuff and focus on the outright crap.

"with your comparison of CMH to T5's while you claimed CMH won't grow large lower flowers." Preposterous. Never made any statement that remotely resembles such an assertion. What I actually stated, were you interested in the truth, is that higher intensity lights than T5 will produce greater yield. Is that arguable? I think not.

"to which you commented that Gavita is the best" I stated that Gavita would outyield a CMH due to the greater intensity of the point source. No comments regarding other DE systems were made as they are irrelevant to the thread topic.

"god's gift" You are really being an ass with this. Spare my your paraphrasing.

"I showed how your claims about penetration as it relates to wattage aren't correct" What you showed is that an irrelevant lighting setup is non-linear at different wattages. Well, no shit.

"I'm not trying to upset you, I'm simply trying to post provable facts." Great. Would you mind keeping your provable facts entirely relevant to the thread topic? Thanks.

"radiation intensity is one of the (if not the) most important factor (e.g. even with an optimized spectrum if PPF is too low results will be poor)." Beta, in my view, that is the single most important statement you have made.

Looking at some of the CMH products offered at GrowersHouse, the Sun System LEC 630 is advertising 33,000 lumen output for only $925.

Lux: I have a Gavita Digistar 1000w, plantmax DE bulb, and Hydrofarm XT3DE wing reflector. Total cost at the time of my purchase was about $250 ballast, $52 bulb, $80 reflector for a total of $382. Output of the plantmax bulb is advertised at 150,000 lumens and I have no reason to doubt it.

That setup replaced a Hortilux 1000w HPS, xtrasun dial-a-watt, daystar reflector.

Based on the results I have obtained, I will not be going back to HPS SE.

One caveat: I have not experienced any RFI issues despite the fact that the ballast is remote from the reflector. However, I live in a rural area and there are no amateur radio operators.

Furthermore, I did some intensity testing of the Gavita dialed-down to 600w vs. a 600w phantom w/USHIO HPS bulb. The Gavita had the greater intensity, as would be expected since it is a high frequency ballast. That dial-down flexibility is not to be overlooked.

Good job bluerock, I'm sure you've convinced yourself you're correct.

interesting topic. Ive always run 600hps and 1000hps aircooled.. but will prob be makin the switch to gavitas and a sealed room in the future. hopefully these cmh's prove themselves to be better.. im open minded, whatever's more efficient and produces proper nugz.

Beta Test Team said:

Good job bluerock, I'm sure you've convinced yourself you're correct.

Click to expand...

Thanks for your statement regarding intensity, Beta. My findings concur. IMO, plant lighting is an area where "cargo cult science" has run amok.

I was being sarcastic.

luxcultivars said:

Fair enough. I appreciate the input. Glad to see things staying civil. Too many ruined threads; just hoping to avoid digression.

Anyway, IME pruning away fans to get stronger light to the lowers mainly just makes them a darker green, and has a minimal effect on total density and yield. I do it all the time. I agree to disagree on the overall significance of that. I think it is likely fairly strain-dependent. I never see any larfy lower flowers but I'm admittedly using Eye-Hortis right now.

As far as the 315w single vs. the 630w double, well, yeah. I'm not going to spend the extra cash on two 315s when I can use a double-bulb fixture like the DimLux or Sun System. The main downside of a bit of light loss will be... that I have to lower the fixture a bit more? That doesn't bother me much. Everyone's mileage will vary there. I would love to buy eight Greenbeams. The cost difference is $2800 for four DimLux 630s or $4,800 for eight Greenbeams and bulbs. Not a tough choice there. The Sun System 315s are better at ~$450 each, but I still lean towards the 630 fixtures.

Everything I read in various forums says that personal results show these 630s to be fairly close to a 1000 HPS in terms of yields and quality and footprint. I am going by other people's experiences here. BTT obviously knows the specifics more than I do.

I would also like to mention that I have made a serious effort over the last two years to stop spending so much energy chasing that '5% better' dragon. As you know, if any given light fixture reaches a certain point of effectiveness, more output beyond that isn't necessarily better. If I can light a 48" x 48" area with a double CMH and maintain my current output and quality, I'd do that over the Gavita for obvious reasons. If I can't... well, here I am. That's why I'm asking.

I admit a lack of personal knowledge/experience about the CMH, so all with a grain of salt. I do like what I have heard, though. All I ever seem to hear from Gavita buyers I know is 'hot spot'. I can see Gavitas as probably being preferable in a warehouse situation. But in an 8' x 8' breeding room?

Click to expand...

If I could just jump into the conversation for a moment and offer a suggestion? The part in bold. If you put that DE Gavita on light movers, wouldn't you eliminate the hot spots, increase coverage area, and increase canopy penetration?


I'll add this link http://cpl.usu.edu/files/publications/publication/pub__8264567.pdf

I think another thread had this discussion with this link as the main topic. Very informative study on cost of fixtures vs. par photons produced, ect. The table on page 6 is also informative, going over comparisons of HPS, LED, and CMH 315's.

Beta Test Team said:

I was being sarcastic.

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Obviously.

iBogart said:

If I could just jump into the conversation for a moment and offer a suggestion? The part in bold. If you put that DE Gavita on light movers, wouldn't you eliminate the hot spots, increase coverage area, and increase canopy penetration?

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I have used linear light movers and am no longer a fan of them. It would also depend on which Gavita setup you go with. The "reflector/ballast" combo model would be quite heavy on a light mover. I would also point out that I selected the remote brushed aluminum wing reflector because it is the least concentrated reflector I could find. No regrets on that one.

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.

iBogart said:

I'll add this link http://cpl.usu.edu/files/publications/publication/pub__8264567.pdf

I think another thread had this discussion with this link as the main topic. Very informative study on cost of fixtures vs. par photons produced, ect. The table on page 6 is also informative, going over comparisons of HPS, LED, and CMH 315's.

Click to expand...

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]

Beta Test Team said:

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]

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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.

But back to that university study, it seems like the Gavita DE is king of the hill for cost of luminaire and umol output. 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. 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, as, if I read correctly in this thread, you favor the spectral output of the CMH 315?