Bridgelux EB-series on a 2' x 4' SCROG

graying.geek said:

Hey, SC. Things are as well as expected. Yeah, I'm happy with my EB build, but still haven't been able to use them for a full flowering cycle; just popped a couple of beans this week, but won't put them under the big lights for a few weeks.

4 x 1120mm EB-series on a 2' x 4' would make a good veg light, but would only be adequate for flowering. At 4" above your canopy you're going to get ~375 umol/sqft, but from what I've read, the optimal number is around 1000, +/-. Why not go with 8 of the EBs? I expect your cost will be lower for equivalent umol output.

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I'm leaning towards the Samsung H series. They use the same LED's as the Quantum Boards which I like. If I understand correctly they have 96 diodes which is a 3rd of 1 QB 288, so I'm thinking therefore that 6 strips would equal 2 QB's. That should be adequate in the 4x2 I think.I'll save on the driver as well by not using the F Series.

Regarding the PPF I think 1000 is too high, at least that's what other growers are telling me. 800 seems to be the optimal amount so that's what I'm going to aim for.

StonerCol said:

I'm leaning towards the Samsung H series. They use the same LED's as the Quantum Boards which I like. If I understand correctly they have 96 diodes which is a 3rd of 1 QB 288, so I'm thinking therefore that 6 strips would equal 2 QB's. That should be adequate in the 4x2 I think.I'll save on the driver as well by not using the F Series.

Regarding the PPF I think 1000 is too high, at least that's what other growers are telling me. 800 seems to be the optimal amount so that's what I'm going to aim for.

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So you're asking for advice because...?

graying.geek said:

So you're asking for advice because...?

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'Cos I wasn't sure on how many strips I'd need. I thought I'd need way more than I do if I went for the EB or H series.

StonerCol said:

'Cos I wasn't sure on how many strips I'd need. I thought I'd need way more than I do if I went for the EB or H series.

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Comparing strips and cobs or qb boards is fine but people need to understand that spreading the same wattage out over a bigger area will mean less ppfd. A 550w QB light in a 4'x4' will be more powerful than 550w of EB's or H/F strips assuming you're spreading them out over the entire 4'x4' footprint.
You basically end up needing to lower your strip light because the photons are so spread out they just don't get the penetration of a cob or QB board.

Danielson999 said:

Comparing strips and cobs or qb boards is fine but people need to understand that spreading the same wattage out over a bigger area will mean less ppfd. A 550w QB light in a 4'x4' will be more powerful than 550w of EB's or H/F strips assuming you're spreading them out over the entire 4'x4' footprint.
You basically end up needing to lower your strip light because the photons are so spread out they just don't get the penetration of a cob or QB board.

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While this may make sense intuitively, it's simply not the case. Assuming the low, single digit differences in efficiencies are negligible, 350 W of strips will output the same PPF as 350 W of COBs or QBs. As long as the grow area isn't smaller than the footprint of the light, spreading the strips out to cover the entire canopy is a good thing, not a detriment, because it allows one to have a consistent PPFD across the canopy rather than having a hot spot directly under a point source, like a QB, and decreasing rapidly in photon density as you move to the edges. When I had my strips configured close together down the middle of my grow area, I measured 120K LUX in the middle, just below the light, and 20K LUX at the edges, and had to keep the lights at 10 inches to avoid toasting the buds in the middle of the scrog. Once I spread the strips out, I could lower them down to 4" from the canopy and measured 50K LUX at all points from the middle to all edges, giving me a much more efficient grow area.

graying.geek said:

While this may make sense intuitively, it's simply not the case. Assuming the low, single digit differences in efficiencies are negligible, 350 W of strips will output the same PPF as 350 W of COBs or QBs. As long as the grow area isn't smaller than the footprint of the light, spreading the strips out to cover the entire canopy is a good thing, not a detriment, because it allows one to have a consistent PPFD across the canopy rather than having a hot spot directly under a point source, like a QB, and decreasing rapidly in photon density as you move to the edges. When I had my strips configured close together down the middle of my grow area, I measured 120K LUX in the middle, just below the light, and 20K LUX at the edges, and had to keep the lights at 10 inches to avoid toasting the buds in the middle of the scrog. Once I spread the strips out, I could lower them down to 4" from the canopy and measured 50K LUX at all points from the middle to all edges, giving me a much more efficient grow area.

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I mentioned ppfd, not ppf. Perhaps you're confused about the difference between the two. Of course they will output the same ppf. Spreading the strips out is a good thing depending on your grow style. These strips make a great sog/scrog light but they don't make a good light to grow one huge plant like many people like to grow. If you don't sog/scrog then you either need to space your strips close together or just simply use cobs/qb's.

StonerCol said:

'Cos I wasn't sure on how many strips I'd need. I thought I'd need way more than I do if I went for the EB or H series.

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Do you have a target PPF for your fixture to cover a 2x4 space? I built mine using 7 each 1120mm 3000K strips for about 600 PPF and about 800 PAR max.

graying.geek said:

While this may make sense intuitively, it's simply not the case. Assuming the low, single digit differences in efficiencies are negligible, 350 W of strips will output the same PPF as 350 W of COBs or QBs. As long as the grow area isn't smaller than the footprint of the light, spreading the strips out to cover the entire canopy is a good thing, not a detriment, because it allows one to have a consistent PPFD across the canopy rather than having a hot spot directly under a point source, like a QB, and decreasing rapidly in photon density as you move to the edges. When I had my strips configured close together down the middle of my grow area, I measured 120K LUX in the middle, just below the light, and 20K LUX at the edges, and had to keep the lights at 10 inches to avoid toasting the buds in the middle of the scrog. Once I spread the strips out, I could lower them down to 4" from the canopy and measured 50K LUX at all points from the middle to all edges, giving me a much more efficient grow area.

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GG - could you give us some idea of how the light falls off as you go down? if you are 50K lx at 4", what does it measure at 8" and 16" down?

Danielson999 said:

I mentioned ppfd, not ppf.

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This is what you said:

>A 550w QB light in a 4'x4' will be more powerful than 550w of EB's or H/F strips assuming you're spreading them out over the entire 4'x4' footprint.

So, without inserting any more information into that statement, by "more powerful," you mean...?

nfhiggs said:

GG - could you give us some idea of how the light falls off as you go down? if you are 50K lx at 4", what does it measure at 8" and 16" down?

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Your wish...

Inches LUX
===== ===
4 51000
8 48200
12 45000
16 43000
20 39900
24 30200

It's not falling off according to the inverse-square law I assume due to the light source being spread out and the strips spaced to even out the coverage.

graying.geek said:

It's not falling off according to the inverse-square law I assume due to the light source being spread out and the strips spaced to even out the coverage

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Exactly. That was the point I wanted to demonstrate. The idea that bright, point source lights "penetrate better" than widespread, even illumination is a complete myth. Thank you for being my "Guinea Pig".

graying.geek said:

This is what you said:

>A 550w QB light in a 4'x4' will be more powerful than 550w of EB's or H/F strips assuming you're spreading them out over the entire 4'x4' footprint.

So, without inserting any more information into that statement, by "more powerful," you mean...?

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I prefaced my meaning in the sentence previous to it. It will have more ppfd where many growers need it as opposed to spreading the photons evenly over an entire tent footprint. A person who grows one large plant doesn't care as much about ppfd at the edge of the tent like a scrogger does. Sometimes higher photon density makes more sense than even coverage.

nfhiggs said:

Exactly. That was the point I wanted to demonstrate. The idea that bright, point source lights "penetrate better" than widespread, even illumination is a complete myth. Thank you for being my "Guinea Pig".

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Agree completely. Folks assume that because a point source appears brighter, it must be giving off more photons than a spread light source of equal wattage and efficiency. Simply not true.

Multiple diodes spread over the entire canopy has indeed better penetration as a fewer more powerful COB's.
Just for one reason, the light is so diffuse because of the multiple angles it comes from, that you will measure higher PAR levels in deeper plant sections with more spreaded light.
It's allmost like under the sun or a diffused greenhouse.
This is the reason why QB and strips are so efficient to grow with. Lower distance compensates lower ppfd values as you see above.
Also big meanlined plants with 8-16 branches could profit if you spread the branches a bit more to better use the whole area. Strips also allows you to create a light dome or a sun cloak like setup to get best penetration from all sides.
It's not my beautifulst drawing, but you can see what I mean. Deeper zones get more penetrating light, because the jets quasi comes from all sides "into" the canopy. Only a little part of the light indeed travels "thru" the leaves the most is reflected from one leaf to an other, which is the reason more green light is used in deeper plant sections.

BTW,
6x 4ft F-Series strips mounted on a 12" x 46" frame is a perfect replacement for a 3 QB in a row set-up. Same amount of 561c S6/A1 diodes(864), same footprint and frame size and same wattage.
You could even use the same drivers only a different voltage is needed.(48v instead on 54v).

You could also use 4x 1ft/280mm double row strips(72 diodes) and put them tightly together on a 300x 160mm heatsink to make it even smaller as a QB is but this creates only a brighter hotspot directly under the light and you'll lost the profits of the better spread.

BuddyColas said:

Do you have a target PPF for your fixture to cover a 2x4 space? I built mine using 7 each 1120mm 3000K strips for about 600 PPF and about 800 PAR max.

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That's the kind of numbers I'm after. Which strips did you use, EB or Samsung?

Danielson999 said:

I mentioned ppfd, not ppf. Perhaps you're confused about the difference between the two. Of course they will output the same ppf. Spreading the strips out is a good thing depending on your grow style. These strips make a great sog/scrog light but they don't make a good light to grow one huge plant like many people like to grow. If you don't sog/scrog then you either need to space your strips close together or just simply use cobs/qb's.

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Don't forget that these strips come in 1ft, 2ft and 4ft so you could use the smaller ones if you only have 1 large plant.

Just saw that there are now Q Series Samsung strips......it's getting confusing lol

graying.geek said:

Your wish...

Inches LUX
===== ===
4 51000
8 48200
12 45000
16 43000
20 39900
24 30200

It's not falling off according to the inverse-square law I assume due to the light source being spread out and the strips spaced to even out the coverage.

Click to expand...

Yupp,
inverse-square law applies here also, but is obsolete because there are so many overlapping from multiple light sources it's allmost impossible to calculate.
But if you increase the distance to say we 2 or 3 meters and the whole lamp acts like a huge COB, you will notice that inverse-square law is better applicable.

StonerCol said:

Just saw that there are now Q Series Samsung strips......it's getting confusing lol

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Where? With LM301b?
I bought 26 2ft. F-Series strips the day before yesterday, would be a shame if there were better strips today, LOL!
I've been waiting for 3 months on strips with new LM301b, but top bin yields does not seem good enough yet, and until now only rolls with different flux bins available but no finished products.