LED vs vertical HPS (PPF and other things)

I see a lot of LED vs HPS comparisons using PPF as a base.

My question is, a HPS bulb outputs light (photons) in all directions (360 degrees), whereas LEDs appear to be reflected off a base (behind the junction) and through a lens limited to 180-degree plane.

So how is PPF determined in each case? Is it total - hypothetical - PPF produced by each LED taking into account refractive and reflective losses (off the reflector/through the lens), and are HPS bulbs equally measured for total PPF in all directions (total hypothetical output), or are hood-mount reflectors taken into account?

The reason I ask is because HPS bulbs can obviously be hung vertically to take advantage of 360-degree light output, whereas hood-mounted horizontal designs lose a substantial amount of light to the imperfect reflective surface, extra distance traveled by each reflected photon, and in many cases, refractive losses through a glass cover.

There is no doubt LEDs are the future of growing and I wish to adapt sooner, rather than later. However, my typical HPS vertical grows are in the 1.3-1.4gpw range, while I've seen more advanced set-ups yield in excess of 2gpw. I'm not sure I've yet seen that in an individual LED grow. Maybe I've been looking in the wrong places?

We're about to set up a reasonably sized commercial grow - 3600-4800w of vertical HPS - and I am having a hard time convincing the other party that perhaps we should plan a horizontal style grow in preparation for a transition to LEDs, which are already coming down in price and improving in efficiency.

How would you convince him?

I think if you are going to stay HID, go with CMH rather than HPS. LED is going to be costly as a startup, your insurance company isn't going to let you DIY LED, I dont know that for a fact, but I would expect that the insurer would want to know the equipment was commercial grade, certified, IP rated. etc.

CMH is apparently more efficient (electricity bills) than HPS and while I have no experience with it there are many who seem to think its the bomb.
https://www.google.com/search?q=ceramic+metal+halide+grow+journal

https://www.rollitup.org/attachments/img_20170722_235331-jpg.3986934/
from this thread
https://www.rollitup.org/t/grandmaster-level-hlg-quantum-boards-vs-1000w-hps-side-by-side-youtube.945508/

That is a new design that will be resealed soon, Quantum Boards would be the way you want to go if you go LED

If I were you I would approach it like any business project. Put together an RFQ that states your objectives, timeframe etc and get quotes from all three technologies, HPS, CMH and LED. Remember that LED has a long lifespan (MTBF), doesn't require bulb replacements and could potentially pay for itself electrically within a 3-4 years.

The other thing here is that you already know how to grow with HID (have your process down, dialed in etc) and as a business you want to be operational asap so in this case I would maybe stick with HID until cash flow isn't an issue then start experimenting with LEDs/Quantum boards or whatever latest and greatest LED tech is out at that time.

canadian1969 said:

The other thing here is that you already know how to grow with HID (have your process down, dialed in etc) and as a business you want to be operational asap so in this case I would maybe stick with HID until cash flow isn't an issue then start experimenting with LEDs/Quantum boards or whatever latest and greatest LED tech is out at that time.

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That is his argument.

For pure flowering, there doesn't appear to be any advantage to running CMH over HPS, and we already have quite a number of 600w hps digital ballasts and access to good, cheap bulbs.

When I say "commercial", I don't actually mean "legal" As this is a long-running venture, continuity is key. The grower in question can't afford to drop yield while transitioning to a new grow room. I don't grow myself any more, but did so for many years on a reasonable scale. I've offered to help him set up, as he wants to base his new grow-room on my old vertical system.

The thing is that with an HPS bulb you lose between 18% and 25% on the reflector. So when you remove that reflector and use a bare bulb indeed your yield per W will go up.

Still, the best single ended HPS bulbs will produce 1.8 to 1.9umol/s/W. A COB will easily produce 2.3 to 2.4umol/s/W. So with COBs (or similar SMDs) you'd have around 25% more light from the same amount of electricity used by HPS.

I was getting 1 to 1.1g/W with horizontal double ended HPS grows and with COBs I moved up to 1.4 to 1.5g/W. That's with older model COBs, current ones are already 10% to 15% more efficient.

Double-ended HPS bulbs are out for two obvious reasons: it's almost impossible to hang them vertically, and the set-up we use - with a floor fan blowing directly up the bulb, creating a cool column of air that allows us to get the plants in closer - wouldn't work anyway, as DEs need to burn hotter and don't like direct cooling.

Playing devil's advocate for a moment, even with a DE bulb, 1.1gpw from a horizontal set-up is not shabby at all - you obviously have experience as a grower. But 1.4-1.5gpw is still well within the realms of a decent vertical HPS grow. My yields were a result of multi-cropping - I grew up to four different strains in a six-plant arrangement around two vertically hung 600w bulbs.

One of my last grows (apologies for the broken links - thanks RIU!) was documented here, and was an average 54oz grow with four different strains: https://www.rollitup.org/t/haze-harvest-a-few-pounds-of-1200w-vertical-weed.668796/

Now, mono-cropping his favourite commercial strain, my friend is starting to get close to these yield with his existing horizontal set-up (24-25oz per 600w hooded HPS). I believe in a climate-controlled room with three to four 1200w (2x600w) vertical HPS stations with overlapping light and monocropping, we can easily nudge 2lb per station - 1.5gpw.

Your PPF figures look about right to me, but for flowering, most HPS light is in the desired spectrum, whereas I believe 2700-3000K type LEDs are not as efficient as 5000K (cool white) type spectra.

So it all comes back to my original question: are LEDs (currently) really as efficient compared to HPS as the numbers suggest? Because in the real world of pure "flower power", it seems they're too close to justify the initial cost of converting to an LED set-up at this stage.

As a concession, I'm looking to do a separate 4x2 horizontal LED grow just to satisfy my own curiosity. However, on paper, it doesn't look like much of a wash to me: the HLG550 costs over US$1K and claims to put out 1265 uMol PPF with 515w. Yet a Son-T Greenpower 600w HPS puts out 1170 uMol at a fraction of the initial cost - not a huge difference, IMO. (I'm aware HPS loses efficiency after 6000 hours, whereas LEDS are good for many times that.)

What do you think?

BTW, I've noticed a lot of LED set-ups in this section are a veg/bloom compromise in terms of spectrum. Most growers I know veg and bloom separately, with dedicated HPS flowering chambers and MH (or other) veg chambers. We are setting up a pure flowering room, so I'm interested in a direct LED/HPS comparison purely for bloom - no compromise or dual use.

Also, we are growing in coco run-to-waste and, for legal reasons, are limited to 10 plants. If we were running an aero vertical scrog, we'd expect better than 1.5gpw.

those are excellent yields you must veg a long time

Prawn Connery said:

So it all comes back to my original question: are LEDs (currently) really as efficient compared to HPS as the numbers suggest?

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yes. ill bet with your technique youd push 2 gpw compared to your setup

Prawn Connery said:

a Son-T Greenpower 600w HPS puts out 1170 uMol at a fraction of the initial cost - not a huge difference, IMO.

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if this is the same bulb its actually 1100 initial umol, about 1050 at 2000 hrs and 1000 at 5000 hrs

http://www.lighting.philips.com/main/prof/conventional-lamps-and-tubes/high-intensity-discharge-lamps/hid-horticulture/horti/928158809227_EU/product

and im pretty sure pulls close to 700W from the wall with the ballast
so 1000-1050 ppf for 700W vs 1265 ppf for 515W at the wall isnt really that close thats like 1.4-1.5 umol/J vs 2.4 umol/J

the real question is does your super high-yielding technique translate to converting to LEDs. it would prob take you a run to get used to the different temp requirements

it would be cool to see you under drive QBs or a bunch of linear strips in place of your hps bulb(s). put them in the cool tube and let aire keep the temps nice and cool so they are nice and bright. or better yet if you were to use linear strips glue em to a water pipe and have zero transmittance losses

Prawn Connery said:

Playing devil's advocate for a moment, even with a DE bulb, 1.1gpw from a horizontal set-up is not shabby at all - you obviously have experience as a grower. But 1.4-1.5gpw is still well within the realms of a decent vertical HPS grow.

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Well that was sort of my point yes. I guess you could equal your vertical HPS results with a horizontal led grow. In fact you should be able to surpass that somewhat since my COBs are well behind on current efficiency. If I used more current COBs I should be able to get more than 1.6 g/W.

Still, it wouldn't give much of a benefit that would warrant the cost. You could do vertical with leds too though. Although I guess you'd gain less than with HPS since leds don't need the reflector anyway.

I agree that it would be wise to test it out first. Since the biggest light loss of HPS is the reflector and wall losses and you pretty much cut those out by going vertical, you would gain less from switching to led compared to horizontal growers.

$1K sounds very expensive for 511W. If you build something yourself using COBs or led strips you should be able to produce a 500W light for around half that price.

even with those same components as the 550 if you get creative with heatsinks

wietefras said:

$1K sounds very expensive for 511W. If you build something yourself using COBs or led strips you should be able to produce a 500W light for around half that price.

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That's just what I've seen them sell for. I would very much like to be in a position to start building my own LED boards, but I still have much to learn and also need to find the time and space to test. That's not going to happen for a while, so at this stage I'm better off purchasing a proprietary system with which to experiment and learn first.

CobKits said:

those are excellent yields you must veg a long time

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With an eight-nine week cylce and separate veg/bloom rooms, you have about six weeks (from clone strike if you take clones during the first week of bloom) to prepare. That's time you can do what you want with, so my grow-on chamber had a 250w MH and I used to mostly hand-water with 1/4=1/3 strength nutes to slow them down a bit.

If going for max yield, the technique would be to boost them to maximise root growth and then prune them just before flower. But with vertical systems it really depends on the strain: what you really want are tall, spindly sativas to make use of the vertical height and fill in from top to bottom. They can be pruned into multi-branch trees, but no so much indicas, which respond better to no topping at all.

CobKits said:

those are excellent yields you must veg a long time if this is the same bulb its actually 1100 initial umol, about 1050 at 2000 hrs and 1000 at 5000 hrs

http://www.lighting.philips.com/main/prof/conventional-lamps-and-tubes/high-intensity-discharge-lamps/hid-horticulture/horti/928158809227_EU/product

and im pretty sure pulls close to 700W from the wall with the ballast
so 1000-1050 ppf for 700W vs 1265 ppf for 515W at the wall isnt really that close thats like 1.4-1.5 umol/J vs 2.4 umol/J

Click to expand...

I agree there are ballast losses with any HPS. I guess what I don't agree with is that the above Quantum Board would replace a 1000w HID as claimed. I would equate it more to the aforementioned 600w HPS.

CobKits said:

it would be cool to see you under drive QBs or a bunch of linear strips in place of your hps bulb(s). put them in the cool tube and let aire keep the temps nice and cool so they are nice and bright. or better yet if you were to use linear strips glue em to a water pipe and have zero transmittance losses

Click to expand...

A vertical LED set-up is what I ultimately have in mind. Why? Because from what I have read - and I am far from well-read on the subject(!) - there is a correlation between refractive losses and lens angle. IE, the tighter the angle (30-60 degrees, say) the more photons are lost compared to a wider angle lens (for example 120 degrees).

Six long boards - say 20cm x 120cm - arranged in a longitudinally hexagonal shape (imagine a hexagonal cool tube arrangement hanging from the vertical, with each of the six sides being 20cm wide and the entire "tube" being 120cm tall - just a rough approximation to give you an idea) would allow each of the 120-degree lensed fixutres to overlap, while the vertical arrangement would capture nearly all the light emitted - even the stray light emitted along the 180-degree plane (think of the LED light you can see at eye-level when looking at a typical horizontal LED board at the same height).

Cooling, as you have correctly identified, would likely be fan-forced through the middle of the hexagonal "tube".

What you have described is essentially what I have been thinking of for some time . . . with a few minor digressions (long, thin boards arranged hexagonally, as opposed to strip lights on the outside of a cool tube or large-diamter pipe).

Please bare in mind I'm a bit old-skool and have been out of the growing game for several years now, but I was an early adopter of vertical growing way back when everyone laughed at it (2003), so I am open to ideas and cognizant of my limited knowledge of LEDs. Things have progressed very quickly.

You can mix light sources, and maybe get something better than any single source by itself. For instance, I mixed HPS with LED and got the benefit of the far red in the HPS and also bumped up the blue spectrum with the LEDs. Growth is crazy, and no bleaching from the LEDs anymore like when I had COBs in there. Now the growth looks more perfect than ever before and is more rampant. You might say that you could just add far red LEDs. Maybe. Never tried them. But HPS is cheap and readily avaiable at Home Depot. Probably need to replace bulbs every 6 months to get maximum output, but it only drops to about 80% at the worst so might as well just settle for the 80% and keep using them until they start cycling on and off. Put a couple more LED bulbs in there if necessary.

I just haven't seen the kind of results I want from LED alone. This mixture, 1 watt LED to 2 watts HPS at present is working great. For reflection, I just put a sheet of aluminum foil about an inch above the bulb and a sheet on each side about 8-9" away at 45 degrees to reflect the side light down. The whole top of the chamber is covered in foil and mylar covers the rest of the inside of the chamber. This is totally working.

BTW if anyone read my posts a while back about putting a "minus green" filter under the HPS to see if it improved growth by altering the spectrum, turned out it didn't work as well as unfiltered. Green light is good for penetrating leaves to the lower parts of the plants. With the filter, it just reduced penetration. Anyway, it was just an experiment I wanted to try, since I had some filters on hand. Experiment concluded. Actually the high green content of HPS may be why it works so well. Probably penetrates inside buds more, making them thicken up.

Evolution has one driver: efficiency within an environment. The most efficient organisms within any environment will thrive the most. Mutation either enhances efficiency or it does not. There are many ways to survive in an environment, but overall success is determined by overall efficiency.

In that respect, plants can grow and thrive under different light sources - but that does not necessarily mean they are the most efficient. For efficiency to be gained, one of two things needs to happen: the plant needs to evolve, or the environment needs to change. As the earth has changed, so different organisms have evolved. Sometimes slowly, sometimes more rapidly. Some evolutionary designs are so efficient, they have changed little over hundreds of millions of years.

In my little grow world, the plants have already evolved, so it is up to me to provide the environment that suits them. That means trying to provide everything they have evolved with. Flowering cycles have evolved with the change of the seasons along the earth's tilting axis and the change in spectra in line with atmospheric conditions. Red/orange light is more predominant at these times, but there is still no shortage of blue/green, UV etc.

More light - any light - is good. But some light is more equal than others at different stages of growth.

That's just my long-winded way of saying you may be on the correct path. If HPS produces red/orange flowering light more efficiently (and that includes total cost) while LED is the most efficient supplier of supplemental light, then perhaps that is a consideration.

However, in the long run, LEDs are at the start of their evolutionary cycle, wheres HIDs are possibly at the other end. If and when LEDs continue to come down in price and go up in efficiency, there will be no contest. I'm not sure if we're quite at that stage yet . . . And I know I'm not the only person who thinks that!

Prawn Connery said:

I see a lot of LED vs HPS comparisons using PPF as a base.

My question is, a HPS bulb outputs light (photons) in all directions (360 degrees), whereas LEDs appear to be reflected off a base (behind the junction) and through a lens limited to 180-degree plane.

So how is PPF determined in each case? Is it total - hypothetical - PPF produced by each LED taking into account refractive and reflective losses (off the reflector/through the lens), and are HPS bulbs equally measured for total PPF in all directions (total hypothetical output), or are hood-mount reflectors taken into account?

The reason I ask is because HPS bulbs can obviously be hung vertically to take advantage of 360-degree light output, whereas hood-mounted horizontal designs lose a substantial amount of light to the imperfect reflective surface, extra distance traveled by each reflected photon, and in many cases, refractive losses through a glass cover.

There is no doubt LEDs are the future of growing and I wish to adapt sooner, rather than later. However, my typical HPS vertical grows are in the 1.3-1.4gpw range, while I've seen more advanced set-ups yield in excess of 2gpw. I'm not sure I've yet seen that in an individual LED grow. Maybe I've been looking in the wrong places?

We're about to set up a reasonably sized commercial grow - 3600-4800w of vertical HPS - and I am having a hard time convincing the other party that perhaps we should plan a horizontal style grow in preparation for a transition to LEDs, which are already coming down in price and improving in efficiency.

How would you convince him?

Click to expand...

Why not use Samsung hard strips mounted on cylindrical posts creating the same 360 degree approach and compare apples to apples. Hard strips produce as well as other forms of Samsung diodes.
Think of a hexagon tube with strips attached on each face with a small fan drawing air up the tube and out. More light less heat to remove.

Prawn Connery said:

BTW, I've noticed a lot of LED set-ups in this section are a veg/bloom compromise in terms of spectrum. Most growers I know veg and bloom separately, with dedicated HPS flowering chambers and MH (or other) veg chambers. We are setting up a pure flowering room, so I'm interested in a direct LED/HPS comparison purely for bloom - no compromise or dual use.

Also, we are growing in coco run-to-waste and, for legal reasons, are limited to 10 plants. If we were running an aero vertical scrog, we'd expect better than 1.5gpw.

Click to expand...

You can mix spectrum. For instance on my GrowGreen boards I mix 5000k with either 3000k or 3500k and either works well for both veg and bloom.

Long time prawn.........arb says hello.
Led does not seem geared towards vertical and considering your level of experience I would be shocked if LEDs even came close to what you're used to seeing.
They do do well in a traditional flat canopy if you either spend up front or build your own out of quality parts.

^ I'd recognise that avatar anywhere! How you going mate?

I know there isn't as much efficiency to be gained from vertical over horizontal LED compared to HID, but I still have this nagging feeling it might work for the reasons above - even narrow-beam LEDs produce stray/ambient light that could be harnessed in a vertical set-up, while my understanding is wide-beam LEDs are more efficient (produce more photons) than narrow-beam. Wide-beam LEDs would be perfect for a vertical set-up. Then there is the columnular cooling that I like to employ and has served me well over the years in my rather hot climate.

As you know, I'm a bit of an old dog myself, so I'd really like to get on top of the whole LED phenomena even if it's not quite ready to displace HPS just yet. I mean, the only way to know is to try, right? I'm actually looking at setting up a smaller horizontal LED grow soon to sate my curiosity and start learning.

You wanna help me with a build?

Oh, and there's another good reason to go vertical - you know how much I love my Haze!

VegasWinner said:

Why not use Samsung hard strips mounted on cylindrical posts creating the same 360 degree approach and compare apples to apples. Hard strips produce as well as other forms of Samsung diodes.
Think of a hexagon tube with strips attached on each face with a small fan drawing air up the tube and out. More light less heat to remove.

Click to expand...

Yes, I have been looking at hard strips. Can you post or link me something reliable? I want full spectrum in the 2000-3000k range with UV and far red. Not a lot of UV, just a bit.

Six thin heat-sinks - maybe 3-4"x48" - hinged into a hexagonal tube is what I'm thinking. I'm not sure when I'm going to get around to the vertical set-up I have in mind, but I want to get a 4x2 horizontal growing going soon. I'm not sure I want to buy proprietary if I can assemble something myself with my desired spectrum. Something in the 400-500w range purely for flowering. I'm happy to buy a 100-150w 4000-5000k off-the-shelf board for vegging - that will be going into a 2.5x2 chamber. The 4x2 bloom and 2.5x2 veg are all I have space for at the moment.

Lol you don't ask for much. I have a supplier in China his name is Roget Zhang with Shenzhen Mufu Technology co ltd on Alibaba he does flexible/hard strips constant current constant voltage various spectrum all within Samsung availabilities including various colors 380nm to 830nm. I get his link but you can google him on Alibaba

Prawn Connery said:

Yes, I have been looking at hard strips. Can you post or link me something reliable? I want full spectrum in the 2000-3000k range with UV and far red. Not a lot of UV, just a bit.

Six thin heat-sinks - maybe 3-4"x48" - hinged into a hexagonal tube is what I'm thinking. I'm not sure when I'm going to get around to the vertical set-up I have in mind, but I want to get a 4x2 horizontal growing going soon. I'm not sure I want to buy proprietary if I can assemble something myself with my desired spectrum. Something in the 400-500w range purely for flowering. I'm happy to buy a 100-150w 4000-5000k off-the-shelf board for vegging - that will be going into a 2.5x2 chamber. The 4x2 bloom and 2.5x2 veg are all I have space for at the moment.

Click to expand...

There is a great diy coop board 200w 5000k/3000k works great in a 2x2. It uses a 185h-c1050b neanwell driver price is cheap but you have to get your own heat sink and driver thread DIY CO-OP lm561c board

Oddly enough I am in about the same space mentally.......but I think its a bit early to go whole hog.
We are selling our spread in the rockies and heading to legal lands.
Going to be building a shop from ground up geared towards the recreational market,the canopy allowed is workable and given the changing legality here I want to be in position to bring my vision to my fellow Americans.