LED vs vertical HPS (PPF and other things)

Enigma said:

One grows along the trellis, the other grows through it.

With vertical you keep the buds on the inside and the leaves on the outside.

Show your maths.

Don't give me Bro-Science.

Based on Maths, cylindrical LED is inferior to panel LED.

It is the opposite for HID.

Click to expand...

There's another issue to keep in mind with cylindrical grows and centrally mounted lighting, I call it the pie wedge or pizza slice problem;

As you leave the trellis panel and grow towards the lamp, your effective surface area shrinks dramatically. Think of a pizza slice; the first inch inwards from the crust is the biggest and each successive inch gets smaller and smaller. Worse, as the plant grows inwards, it shades more and more of the trellis. This is okay if you grow a flat plant plastered to the trellis panel, but the moment your buds start growing inwards you get this problem.

A flat vertical trellis panel lit by an array doesn't have this problem of basic geometry and as we all know, the key to high yields is depth of buds.

wietefras said:

No, that's just a couple of separate flat verticals and it would be completely impossible to actually run that way and reach the plants from all sides. A circle I can turn around.

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I had no such problems. There's more space to work in, not less.

Tim Fox said:

me,,, calling my insurance company,, ring ring ring
insurance company answers the phone,,,
me,,,, hey can we insure my pot grow,,
insurance company,,,,, click,,, ring tone

Click to expand...

Dude said [erroneously] "commercial grow", I took that to mean legal and licensed and by extension insured.

^ I know. And it is a completely reasonable assumption, considering growing is legal in many parts of the US now. But unfortunately, I'm in Australia, and when I say "commercial" I really mean growing pot illegally for money. That's my friend - he doesn't even smoke - so he needs someone like me to help him nail the quality. I get as much free weed as I can smoke. Which has been handy since I had to pack up my own grow a few years ago. I started off as a personal grower and got sufficiently good at it that I could supply a small circle of friends to help pay my costs and make it a little more worthwhile. So I always had a few different strains going for variety, which is less efficient than monocropping, but much more worthwhile!

I do enjoy these debates

Now the antithesis of the "pie chart" chart law is the inverse-square law. It simply states that every time you double the distance of a light source, you halve the energy through spherical dispersion. So with a single light source, the edges and corners of a square trellis get the least amount of light, as it geometrically must travel further to get there.



For a single light source, a sphere is the most efficient trellis dimension, as equal light is distributed across all surface areas. With a HPS bulb - which is cylindrical - a tube is the most efficient shape.

I know that vertical trellis growers such as ttystikk use multiple light sources, but I'm just explaining the theory - which you guys probably already know

In practice, vertical grows are not very dense - and they are very much a scrog. While the buds do get thicker, and they do move towards the light creating a "pie wedge" effect, they mostly grow up along the cylindrical trellis and as buds form, the grower (me in this case) weaves the branches horizontally and vertically into the trellis to fill in any gaps. The plants themselves end up being somewhat of a fan shape, spread out and around the trellis (I actually call it a "cage") as in the photo below. (One of the buds has been pulled to one side to show the position of the 600w HPS bulb. There is another 600w bulb down the bottom, in the middle of all that tangle.)




The plants themselves look like this - tall, sticky branches that are somewhat fanned out (bunched together a little bit in this photo to stop the branches falling off to the sides and snapping under their own weight):




The interesting thing about LED light dispersion is that many of you have seen these charts:




This one is typical of a 120-degree angle LED light source. It's also a bit misleading, as there is ALWAYS ambient light that falls outside the ranges provided. Here is a more accurate depiction of LED light distribution. Remember, these are only examples to highlight my point - I'm not arguing the merits of individual LEDs:




So what happens to all that light that emits between the 180 degree plane of the light source (the perfect horizontal) and the canopy, which at the most (depending on how close you can get your lights to the canopy) falls within that 120-degree angle? Even in the first diagram you can see a lot of strong light falling outside the 150-degree and 30-degree planes (representing the limit of the 120-degree splay).

What else is interesting is, notice how the light intensity is curved, almost like a perfect circle? This also demonstrates what I mean about the sphere or cylinder being the most efficient shape for a single light source, as light intensity is spread equally around the circle.

This all seems obvious with a HPS bulb that emits in 360-degrees. But what I have shown above leads me to believe there are efficiencies to be gained with vertical LED in a cylindrical or hexagonal shape. A cylinder would probably be best, but a hexagon would be a good compromise with 120-degree LEDs, as the diameter of the plants would likely coincide with where the 120-degee beam angles converge on each of the six sides.

I also believe 120-degree LEDs have less refractive losses - and are more efficient - than narrower-angle LEDs, making them an ideal choice.

I like the idea of a flat trellis vertical grow to make use of head height - the results speak for themselves. But respectfully, it is for the most part a horizontal grow turned on its side with the same geometry. And while a cylindrical grow could be seen as compromising a square footprint, remember, you need to access your plants if you are going to scrog them. A cylinder allows access from all sides.

Of course, this is all hypothetical on my part in relation to LEDs as I have not done it yet.

Prawn Connery said:

This one is typical of a 120-degree angle LED light source. It's also a bit misleading, as there is ALWAYS ambient light that falls outside the ranges provided.

Click to expand...

chart is actually right on the money

chart shows light up to 0/180 degrees and none beyond. and you can see the 10% intensity at 15/165 degrees. if you were to integrate that whole graph youd see about 90% of the light falling in the 120 degrees mfrs and customers generally consider cobs to radiate

The only problem I see is getting inside the cylinder unless you use two or more plants that can be moved independently.

With the Wall of Green you get more surface area and the same independent movement.

The biggest problem using a cylinder with COBs is the intensity, something like EBs would fair better in my estimation.

I can see HIDs being close with proper air movement.

In the set-up above, there is a 12" floor fan blowing directly over the two bulbs, with an extractor fan directly above. This creates a cool column of air - a boundryless cool tube - that directly ducts heat away from the bulbs and also creates enough airflow for the plants to prevent bud rot. This allows the plants to get very close to the bare bulb, as you can see.

I tried glass cool tubes, but they got dirty quickly and had no appreciable effect on cooling compared to bare bulbs. Not only did the glass get dirty, the extra layer of glass itself cut some light.

You don't really need to get to the inside of the cylinder. If a branch or bud starts getting too close, you pull it out from the back, a branch at a time. Same goes for if you want to remove fan leaves growing into the light - pull out a branch, reach through the gap, pull off the leaves etc. As I mentioned, the vertical canopy itself is not very thick.

Also, surface area is subject to the law of diminishing returns, so there are basically two variables - light and surface area. You can either increase/decrease the amount of light, or increase/decrease the amount of surface area to achieve the correct balance.

Of course, the above variables can be tweaked by making more efficient use of the available light - allowing you to increase the surface area - or making the plant itself more efficient (CO2) allowing an increase in usable light for the same area.

Basically, surface area is only as useful as the light source and photosynthetic efficiency.

CobKits said:

chart is actually right on the money

chart shows light up to 0/180 degrees and none beyond. and you can see the 10% intensity at 15/165 degrees. if you were to integrate that whole graph youd see about 90% of the light falling in the 120 degrees mfrs and customers generally consider cobs to radiate

Click to expand...

That's good to know. I picked a random chart to prove a point, so I didn't know how accurate it was. At a glance - looking at the surface area of the 30-150 degree coverage compared to the remainder - I can agree with what you're saying. So maybe there's a 10% efficiency to be gained. I don't really know. With HPS, you're probably losing 25-30% of light intensity with a hood due to reflective and ambient losses.

I probably need to quantify what I said earlier as well. Unless I am mistaken, that chart shows light intensity at various angles, but those angles are tangental to the light source. Unless your horizontal grow is curved - dish-shaped - then not only do you lose light intensity from the LED beam angle, but also with the extra distance it has to travel to reach the horizontal surface at either extreme.

Sorry for all the edits

It's worth noting my set-up really favoured sativas. They would grow tall and branchy, and end up fanning out around the top of the cage. I love growing sativas, so that was primarily why I built my vertical box with stacked 600w bulbs.

The indica hybrids used fill the gaps between the sativas down the bottom and didn't need so much weaving or scrogging - they sort of just sat there and bulked up. This meant I could always pull an indica out without disturbing the rest of the grow if I needed to get to the inside of the cage.

The arrangement around the cage looked a bit like this, where the "V" is a fanned out sativa, and the "o" is a dumpy indica: VoVoV

And here's what the same room looked like when I removed the three catpiss hazes, leaving three Calizahr X Schnazzleberry crosses and a Swiss Bliss (this was a seven-plant grow). The Swiss Bliss is at the back - I love that strain! - while the little indica crosses used up most of the bottom light, and the catpiss hazes used up most of the top. You can see the floor fan at the bottom. Leaf burn at bottom right was a bit of wind burn from the leaves rubbing up and down against the cage near the fan, but also due to pushing the limits on my nutes. All these plants were fed from the same reservoir, so some handled the nutrient solution better than others:



I had to pull these pix out of my other thread. I used to have lots of other photos and documented grows, but they all went into the ether when I lost my old site at planetganja.com

Prawn Connery said:

I do enjoy these debates

Now the antithesis of the "pie chart" chart law is the inverse-square law. It simply states that every time you double the distance of a light source, you halve the energy through spherical dispersion. So with a single light source, the edges and corners of a square trellis get the least amount of light, as it geometrically must travel further to get there.

View attachment 4008537

For a single light source, a sphere is the most efficient trellis dimension, as equal light is distributed across all surface areas. With a HPS bulb - which is cylindrical - a tube is the most efficient shape.

I know that vertical trellis growers such as ttystikk use multiple light sources, but I'm just explaining the theory - which you guys probably already know

In practice, vertical grows are not very dense - and they are very much a scrog. While the buds do get thicker, and they do move towards the light creating a "pie wedge" effect, they mostly grow up along the cylindrical trellis and as buds form, the grower (me in this case) weaves the branches horizontally and vertically into the trellis to fill in any gaps. The plants themselves end up being somewhat of a fan shape, spread out and around the trellis (I actually call it a "cage") as in the photo below. (One of the buds has been pulled to one side to show the position of the 600w HPS bulb. There is another 600w bulb down the bottom, in the middle of all that tangle.)

View attachment 4008540


The plants themselves look like this - tall, sticky branches that are somewhat fanned out (bunched together a little bit in this photo to stop the branches falling off to the sides and snapping under their own weight):

View attachment 4008541


The interesting thing about LED light dispersion is that many of you have seen these charts:

View attachment 4008544


This one is typical of a 120-degree angle LED light source. It's also a bit misleading, as there is ALWAYS ambient light that falls outside the ranges provided. Here is a more accurate depiction of LED light distribution. Remember, these are only examples to highlight my point - I'm not arguing the merits of individual LEDs:

View attachment 4008545


So what happens to all that light that emits between the 180 degree plane of the light source (the perfect horizontal) and the canopy, which at the most (depending on how close you can get your lights to the canopy) falls within that 120-degree angle? Even in the first diagram you can see a lot of strong light falling outside the 150-degree and 30-degree planes (representing the limit of the 120-degree splay).

What else is interesting is, notice how the light intensity is curved, almost like a perfect circle? This also demonstrates what I mean about the sphere or cylinder being the most efficient shape for a single light source, as light intensity is spread equally around the circle.

This all seems obvious with a HPS bulb that emits in 360-degrees. But what I have shown above leads me to believe there are efficiencies to be gained with vertical LED in a cylindrical or hexagonal shape. A cylinder would probably be best, but a hexagon would be a good compromise with 120-degree LEDs, as the diameter of the plants would likely coincide with where the 120-degee beam angles converge on each of the six sides.

I also believe 120-degree LEDs have less refractive losses - and are more efficient - than narrower-angle LEDs, making them an ideal choice.

I like the idea of a flat trellis vertical grow to make use of head height - the results speak for themselves. But respectfully, it is for the most part a horizontal grow turned on its side with the same geometry. And while a cylindrical grow could be seen as compromising a square footprint, remember, you need to access your plants if you are going to scrog them. A cylinder allows access from all sides.

Of course, this is all hypothetical on my part in relation to LEDs as I have not done it yet.

Click to expand...

I considered this, too- and the reason I went with a flat panel was trifold; first, the cylinder kept all the geometric disadvantages of the pie wedge problem. If you're just going to run a vertical strip of LED lights you're going to get the same shape result.

Second, it ignores the benefits of arrays in terms of light distribution across the canopy surface. This is why LED light arrays grow such nice even canopies from edge to edge. The multi point source nature of arrays also greatly reduces leaf shading, allowing for better production through the depth of the canopy.

Having tried to work on the plants exclusively from the outside of the cylinder, I can tell you it doesn't really work. You need to see it from the point of view of the light source to do a good job and that means getting inside- and that's a cramped pain in the ass.

Therefore, a flat vertical panel lit by an array is more space efficient and improves the productivity of those working on it.

I'm not raining on your parade, I'm just trying to save you from reinventing the wheel.

Have you seen this one, I have to think this is about as energy efficient and yield maximizing as you can get.

thats not a vertical as we are discussing here, most people would call that a shelf garden, but im sure that absolutely crushes on yield!

ttystikk said:

I'm not raining on your parade, I'm just trying to save you from reinventing the wheel.

Click to expand...

I know and appreciate the input. Don't worry, I've got a pretty thick shell!

I'm really just thinking out aloud here, based on something I know (vertical growing) vs something I am still very much coming to terms with (LED grows). Like anything, I guess we all find what works best for us, but as Issac Newton said, it's good to stand on the shoulders of giants . . . or something like that.

BTW, I think you're familiar with a Canadian guy on these boards named sezar29 - he's the bloke with the styrafoam vertical aeroponic SOG with HPS/MH and C02. Met him on RIU a few years ago and he was (probably still is) getting 2.15gpw.

As the Canuks say: "Fuckin eh!"

He admitted it was a lot of work, though.

CobKits said:

thats not a vertical as we are discussing here, most people would call that a shelf garden, but im sure that absolutely crushes on yield!

Click to expand...

Yeah, the terminology is a bit weird, I hear that (SGS video) referred to as "vertical farming" in the industry publications like LED magazine etc , I am following what you guys are talking about though. I would actually call that "stacked horizontal / low profile SCROG" or something a bit more accurate. I guess people are using "vertical" as a classification rather than a style. Or "vertical" encompass several styles? Just as an experiment I google image searched both "vertical farming" and "vertical growing" and you get decidedly different results. Interesting.

Prawn Connery said:

BTW, I think you're familiar with a Canadian guy on these boards named sezar29 - he's the bloke with the styrafoam vertical aeroponic SOG with HPS/MH and C02. Met him on RIU a few years ago and he was (probably still is) getting 2.15gpw.

As the Canuks say: "Fuckin eh!"

He admitted it was a lot of work, though.

Click to expand...

arent all the vertical grow gpw somewhat inflated by nature due to the long veg times?

CobKits said:

arent all the vertical grow gpw somewhat inflated by nature due to the long veg times?

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No. Fewer, larger plants don't perform as well as more smaller plants covering the same area.

https://smartgrow.systems/systems/

this is pretty cool..he must have copied eeryone here..≥[joke]

OLD MOTHER SATIVA said:

https://smartgrow.systems/systems/

this is pretty cool..he must have copied eeryone here..≥[joke]

Click to expand...

just checked out smartgrowsys on ig... crushin it

CobKits said:

arent all the vertical grow gpw somewhat inflated by nature due to the long veg times?

Click to expand...

The Canadian bloke I quoted has a vertical sog - as opposed to scrog - and basically flowers rooted clones. The Dutch perfected the sea-of green technique (as opposed to the sea cover of green, which trains fewer plants into an even canopy) because for the most part they didn't have to worry about plant numbers.

As ttystikk noted, large numbers of smaller plants have a higher total root mass and always yield better than fewer, larger plants. The most efficient vertical grows are actually the stadium style sogs that use multi-level aeroponic or NFT systems to flower large numbers of rooted clones.