SpiderFarmer SE3000 PPFD Chart, Accurate?

[dbrzz]

I have a sf4000, I have a 4x4. This light @ 100% output, has the best growth rate @ 24 inches. This height has optimum photon spread across the space. The edge ppfd is approx. 507 and the center is 850.
View attachment 1183971
View attachment 1183971

The big cola is 5 inches from the light and is light stressed and showing damage. Its a sacrificial bud and experiment of light stress symptoms. Also the younger plants are in the 24-30 inch zone and will grow better. Since I have used this light, I have the best growth using the light @ 24 inches above the plants or canopy when it grows. 20% power @ 24 inches for sprouts, unless they stretch, then increase the power to 30%. 20% every 2-3 days until full power, then maintain 24 inches without defoliation, and you will fill the space edge to edge with big colas outside as well as inside the sweet spot. 2 five gallon pots is all I have room to grow. I like a simple productive low maintenance garden. I get 10 or more ounces of dried cured bud every 90 days so yield is good enough for me.

 

[Dothraki]

Hello. I've been reading your thread and may I just interject that the formula for calculating what your PAR/PPFD at any given distance change is what is known as the Inverse Square Law applicable to all forms of light, visible and invisible. Hope this helps. Intensity 1 over Intensity 2 = Distance 2 (squared) over Distance 1 (squared) Just set up the equation as I have it here, square your Distances 1 & 2 and then cross-multiply. Results will demonstrate mathematically that when you reduce the distance by 1/2 you increase the light intensity value X 4 Conversely if you double the new distance from the light source you will end up with 1/4 the light intensity. You can review the Inverse Square Law online and get a working formula where you can plug in your own values.

​

Awesome! That’s exactly what I was wondering with distance & intensity. Soo to make sure I’m understanding correctly... @dbrzz is 850 PAR at 24”, so if he dropped down to 12” he’d be at 3400 PAR and at 18” 1700, etc. is that correct?

 

[Dothraki]

The big cola is 5 inches from the light and is light stressed and showing damage. Its a sacrificial bud and experiment of light stress symptoms. Also the younger plants are in the 24-30 inch zone and will grow better. Since I have used this light, I have the best growth using the light @ 24 inches above the plants or canopy when it grows. 20% power @ 24 inches for sprouts, unless they stretch, then increase the power to 30%. 20% every 2-3 days until full power, then maintain 24 inches without defoliation, and you will fill the space edge to edge with big colas outside as well as inside the sweet spot. 2 five gallon pots is all I have room to grow. I like a simple productive low maintenance garden. I get 10 or more ounces of dried cured bud every 90 days so yield is good enough for me.

Hell yes! That sounds like a sweet workflow and a helluva lot of bud lol. So did you go by the spider farmer SF4000 chart? How did you figure the general distances out before adjusting by, I’m assuming plant growth?

 

[dbrzz]

Awesome! That’s exactly what I was wondering with distance & intensity. Soo to make sure I’m understanding correctly... @dbrzz is 850 PAR at 24”, so if he dropped down to 12” he’d be at 3400 PAR and at 18” 1700, etc. is that correct?

Hell yes! That sounds like a sweet workflow and a helluva lot of bud lol. So did you go by the spider farmer SF4000 chart? How did you figure the general distances out before adjusting by, I’m assuming plant growth?

Hell yes! That sounds like a sweet workflow and a helluva lot of bud lol. So did you go by the spider farmer SF4000 chart? How did you figure the general distances out before adjusting by, I’m assuming plant growth?

Hell yes! That sounds like a sweet workflow and a helluva lot of bud lol. So did you go by the spider farmer SF4000 chart? How did you figure the general distances out before adjusting by, I’m assuming plant growth?

 

[tucume66]

Awesome! That’s exactly what I was wondering with distance & intensity. Soo to make sure I’m understanding correctly... @dbrzz is 850 PAR at 24”, so if he dropped down to 12” he’d be at 3400 PAR and at 18” 1700, etc. is that correct?

Yes, that looks correct. It is important to remember that PAR is a measure of intensity of the amount of photons falling on any given measured surface area and that amount changes based on where under the light the measurement is taken and there is substantial "drop off" on the edges of any LED's light coverage which is why in a 4 X 4 tent I use four 1000 watt dimmable fixtures, essentially one for each large plant which allows for light that is more scattered on the periphery of each light's field to intersect and add more photons the the lower areas as well. Here is a link to another article you may find helpful that discusses PAR and Lumens and there is a section called "why it's best to get over PAR" and includes 4 very valid reasons why PAR is not a true reflection of a light's proficiency and discusses other factors such as IR and UV LEDs. Some lights are not equipped with these frequencies that is proven that plant's need for health and growth during the flowering phase particularly in the case of IR. Dr. Bugbee has several videos that will provide you in depth study supporting what this article is relating. http://www.compareledgrowlights.com/par_and_lumens/

 

[growsince79]

Hello. I've been reading your thread and may I just interject that the formula for calculating what your PAR/PPFD at any given distance change is what is known as the Inverse Square Law applicable to all forms of light, visible and invisible. Hope this helps. Intensity 1 over Intensity 2 = Distance 2 (squared) over Distance 1 (squared) Just set up the equation as I have it here, square your Distances 1 & 2 and then cross-multiply. Results will demonstrate mathematically that when you reduce the distance by 1/2 you increase the light intensity value X 4 Conversely if you double the new distance from the light source you will end up with 1/4 the light intensity. You can review the Inverse Square Law online and get a working formula where you can plug in your own values.

​

That only works when the energy is from a single point. LED boards have hundreds of points spread out. If I put my qb 1 foot above my meter, there is only one chip that is exactly 1' above it. The rest all all more than 1' away. If I raise the board to 2' the distance to that same chip is doubled. The distance to all the other chips increased, but it was less than double. The light angle is also a big factor. So using law of inverse square won't work at all with leds panels/boards..

 

[dbrzz]

I used their recommended 30 inches @ 100% for veg and 18 inches for flower. There are utube videos of actual ppfd value of spiderfarmer lights at different height levels. My experience growing with this light, along with data from these videos of the light photon density spread, at differing heights, has dialed my grow to 24 inches best setting @ 100% output.

 

[Dothraki]

Great, thank you! Unfortunately nobody has done any measuring of the new SE3000 light so I’m hoping not to burn up my seedlings when I start lol. Or make them reach for the sky.

 

[Dothraki]

That only works when the energy is from a single point. LED boards have hundreds of points spread out. If I put my qb 1 foot above my meter, there is only one chip that is exactly 1' above it. The rest all all more than 1' away. If I raise the board to 2' the distance to that same chip is doubled. The distance to all the other chips increased, but it was less than double. The light angle is also a big factor. So using law of inverse square won't work at all with leds panels/boards..

But it can give me a general idea based off of the closest approximations, which is all I can go by at the moment.

 

[Dothraki]

Yes, that looks correct. It is important to remember that PAR is a measure of intensity of the amount of photons falling on any given measured surface area and that amount changes based on where under the light the measurement is taken and there is substantial "drop off" on the edges of any LED's light coverage which is why in a 4 X 4 tent I use four 1000 watt dimmable fixtures, essentially one for each large plant which allows for light that is more scattered on the periphery of each light's field to intersect and add more photons the the lower areas as well. Here is a link to another article you may find helpful that discusses PAR and Lumens and there is a section called "why it's best to get over PAR" and includes 4 very valid reasons why PAR is not a true reflection of a light's proficiency and discusses other factors such as IR and UV LEDs. Some lights are not equipped with these frequencies that is proven that plant's need for health and growth during the flowering phase particularly in the case of IR. Dr. Bugbee has several videos that will provide you in depth study supporting what this article is relating. http://www.compareledgrowlights.com/par_and_lumens/

So in that case the PPFD charts are waaaaay off. Look at the SE3000 chart saying 1199 @ 10” and 1204 @ 8” for that specific square.

 

[tucume66]

That only works when the energy is from a single point. LED boards have hundreds of points spread out. If I put my qb 1 foot above my meter, there is only one chip that is exactly 1' above it. The rest all all more than 1' away. If I raise the board to 2' the distance to that same chip is doubled. The distance to all the other chips increased, but it was less than double. The light angle is also a big factor. So using law of inverse square won't work at all with leds panels/boards..

Technically you are correct when measuring the output of any single LED chip especially at a very close distance of less than 12 inches. Let's just say that there is only 1 LED that is emanating light. That light wants to spread out 360 degrees from it's point source, and the photons from the side not visible are being absorbed as heat in the heat sink of your lamp. You can take measurements of scattered photons from the periphery and they will be far less than those emanating from the exact center of the LED light. Your example of saying that you are measuring the output of only the central LED is not totally correct due to the scattering phenomenon of light mentioned earlier. It is impossible to measure the output of one LED unless you cover all the rest so that light does not emanate from the shield and then your reading will be much different. When you consider an entire light field composed of hundreds of LEDs as a "single point source" or whether you are measuring a small area or single LED the Inverse Square Law always works and the values you get are going to be determined by the location of the group of LEDs that you are taking your measurments under. All adjacent LEDs are contributing scattered photons into the meter when you are even as close as 1 inch to the central LED due to the inherent scattering of photons that is characteristic of all light visible and invisible, which means that this reading will even fluctuate a tiny bit due to the amount of scattering that is hitting the receptor of the measuring device at any given second in time. So all PAR readings are set by the mfg based on an average of readings and may vary with any two lamps of the same model and manufacturer. Here is an article that deals with PAR that you might find interesting. http://www.compareledgrowlights.com/par_and_lumens/

 

[growsince79]

Technically you are correct when measuring the output of any single LED chip especially at a very close distance of less than 12 inches. Let's just say that there is only 1 LED that is emanating light. That light wants to spread out 360 degrees from it's point source, and the photons from the side not visible are being absorbed as heat in the heat sink of your lamp. You can take measurements of scattered photons from the periphery and they will be far less than those emanating from the exact center of the LED light. Your example of saying that you are measuring the output of only the central LED is not totally correct due to the scattering phenomenon of light mentioned earlier. It is impossible to measure the output of one LED unless you cover all the rest so that light does not emanate from the shield and then your reading will be much different. When you consider an entire light field composed of hundreds of LEDs as a "single point source" or whether you are measuring a small area or single LED the Inverse Square Law always works and the values you get are going to be determined by the location of the group of LEDs that you are taking your measurments under. All adjacent LEDs are contributing scattered photons into the meter when you are even as close as 1 inch to the central LED due to the inherent scattering of photons that is characteristic of all light visible and invisible, which means that this reading will even fluctuate a tiny bit due to the amount of scattering that is hitting the receptor of the measuring device at any given second in time. So all PAR readings are set by the mfg based on an average of readings and may vary with any two lamps of the same model and manufacturer. Here is an article that deals with PAR that you might find interesting. http://www.compareledgrowlights.com/par_and_lumens/

Didn't say anything about measureing light output from only 1 diode. I said if you double the distance of the board, you only double the distance of 1 diode not all of them. My point is halving the distance from the board to the canopy will not increase the light 4x like it would with HID. Inverse square formula won't work. At 2', if the ppfd is 300- lowering it to 1' doesn't make it 1200ppfd.

 

[tucume66]

So in that case the PPFD charts are waaaaay off. Look at the SE3000 chart saying 1199 @ 10” and 1204 @ 8” for that specific square.

They could be off if the company doing the measuring is not using a device known as an integrating sphere to measure the PPFD which is measured in micromoles per second and not being familiar with the chart for that model cannot attest to the figures given. Here is an article that really explains the differences between PAR PPFD and Photon Efficacy. https://fluence.science/science-articles/horticulture-lighting-metrics/ Youtube also has several very instructive videos by Horticulturalist Dr. Bruce Bugbee on all these issues and more!

 

[growsince79]

So in that case the PPFD charts are waaaaay off. Look at the SE3000 chart saying 1199 @ 10” and 1204 @ 8” for that specific square.

Not necessarily. They could be right. They put more chips on the edges than the do the center.

 

[tucume66]

Didn't say anything about measureing light output from only 1 diode. I said if you double the distance of the board, you only double the distance of 1 diode not all of them. My point is halving the distance from the board to the canopy will not increase the light 4x like it would with HID. Inverse square formula won't work. At 2', if the ppfd is 300- lowering it to 1' doesn't make it 1200ppfd.

I used one LED diode as an example. The Laws of the Universe (at least the law governing light and it's properties in our world) does not change with HID, LED, Incandescent, Fluorescent, Flashlight or Sunlight. Light from any point source is light, visible or invisible. Halving your distance with any light is absolutely going to increase X4 the intensity and amount of photons hitting your measuring device or your canopy of whatever else who choose to place under that light. The light is measured as PPFD (photosynthetic photon flux density) in the units of mmoles/m2/s and is the measure of how many photons of light, that can drive photosynthesis, are striking a given area every second. This value of PPFD refers to wavelengths of light that plants are photosynthetically sensitive to compared to PAR which is Photosynthetically Active Radiation and is an absolute measurement whereas PPFD is a relative measurement, relative to changes in distance. https://fluence.science/science-articles/horticulture-lighting-metrics/

 

[growsince79]

I used one LED diode as an example. The Laws of the Universe (at least the law governing light and it's properties in our world) does not change with HID, LED, Incandescent, Fluorescent, Flashlight or Sunlight. Light from any point source is light, visible or invisible. Halving your distance with any light is absolutely going to increase X4 the intensity and amount of photon hitting your measuring device or your canopy of whatever else who choose to place under that light. The light is measured as PPFD (photosynthetic photon flux density) in the units of mmoles/m2/s and is the measure of how many photons of light, that can drive photosynthesis, are striking a given area every second. This value of PPFD refers to wavelengths of light that plants are photosynthetically sensitive to compared to PAR which is Photosynthetically Active Radiation and is an absolute measurement whereas PPFD is a relative measurement, relative to changes in distance.

You aren't understanding what I said. When I lower my board from 2' to 1', The distance from the probe centered under the board to the light source isn't halved. The distance is only half to the closest diode directly above the probe. The distance to the outside diodes were not halved. Also the diodes direct light down - not out. When I lower from 2'- 1' the intensity absolutely does not increase 4x - its not even close. Buy a qb and a meter and see for yourself.

 

[tucume66]

I used one LED diode as an example. The Laws of the Universe (at least the law governing light and it's properties in our world) does not change with HID, LED, Incandescent, Fluorescent, Flashlight or Sunlight. Light from any point source is light, visible or invisible. Halving your distance with any light is absolutely going to increase X4 the intensity and amount of photons hitting your measuring device or your canopy of whatever else who choose to place under that light. The light is measured as PPFD (photosynthetic photon flux density) in the units of mmoles/m2/s and is the measure of how many photons of light, that can drive photosynthesis, are striking a given area every second. This value of PPFD refers to wavelengths of light that plants are photosynthetically sensitive to compared to PAR which is Photosynthetically Active Radiation and is an absolute measurement whereas PPFD is a relative measurement, relative to changes in distance.

Photon Efficacy refers to how efficient a horticulture lighting system is at converting electrical energy into photons of PAR. Many horticulture lighting manufacturers use total electrical watts or watts per square foot as a metric to describe light intensity. However these metrics really don't tell you anything since watts are a measurement describing electrical input, not light output. If the PPF of the light is known along with the input wattage, you can calculate how efficient a horticulture lighting system is at converting electrical energy into PAR. As a reminder, the unit for PPF is μmol/s, and the unit to measure watts is Joule per second (J/s), therefore, the seconds in the numerator and denominator cancel out, and the unit becomes µmol/J. The higher this number is, the more efficient a lighting system is at converting electrical energy into photons of PAR.

https://fluence.science/science-articles/horticulture-lighting-metrics/

 

[growsince79]

Incorrectly using the inverse square formala to calculate won't get you the correct numbers. With a HPS, if I move from 18" to 12" the center value should double. Not so with qbs and panels.

 

[tucume66]

View attachment 1184018View attachment 1184019
Incorrectly using the inverse square formala to calculate won't get you the correct numbers. With a HPS, if I move from 18" to 12" the center value should double. Not so with qbs and panels.

In an earlier comment you said "halving the distance from the board to the canopy will not increase the light 4x like it would with HID." But the example you give above contradicts your original statement and is exactly how the ISL works because your distance decrease doubles the intensity which is correct. By extension decreasing the original distance of 18" down to 9" (halving it) would double the intensity again which does equal 4X the original intensity. So the ISL does work in this case.

However upon reconsidering everything I believe you are correct in that the ISL cannot be applied to PPFD as this is a measure of the total number of PAR photons that are available to the canopy measure in micromoles per second per meter squared. I have done the measurements at various heights using a Doctor Lux Meter which is not going to be as accurate in determining PPFD but it will come within a reasonable and usable figure, and although I didn't record those numbers now that I think back on it, the relationship between distance and PPFD is more linear and not inversely proportional. That is my error and I apologize.

 

[tucume66]

So in that case the PPFD charts are waaaaay off. Look at the SE3000 chart saying 1199 @ 10” and 1204 @ 8” for that specific square.

Many PPFD charts can be off due to the manner in which the information is gathered. I was talking with the original respondent you were discussing your issue with and have finally come to the conclusion that I was in error when I stated that the ISL applied to PPFD as that is a measure of the PAR value of light frequences being emitted in micromoles per second per meter squared. I remember having using a Doctor Lux-Meter to measure the output and converted from Lux to PPFD and now that i think about it, the relationship is more linear rather than and inversely squared function. So I apologize for giving you misinformation on that issue.