What is optimum number of lumens at tops?

Loc Dog · Dec 8, 2017

I just switched to Vero 29 Gen7's running at 110 watt each, and heat is not an issue at about a foot from tops, but wondering if too much light is hurting them, and yielding much less. Has anyone determined the optimum lumen numbers?

I am using a lumen meter, so not using reported lumens by manufacturer.

Also, I am poor, so was able to buy a $20.00 lumen meter. I know I should be asking about PAR, but would rather not spend a few hundred I can not afford, to tune things. I am hoping someone with a par meter, has compared to lumens.

Phaeton · Dec 8, 2017

Lumens became the standard of light units back when incandescent lighting was the only choice.
The percentage of green emitted by a hot metal filament was known and the total light could be calculated.
Now the light is emitted by specific mixed phosphors, each with its own specific color. How they are blended determines the spectrum graph.
If no green phosphors are included the lumen count will be nonexistent or very low. If green emitting phosphors are in the majority (residential lighting) then the lumen count will be high but the rest of the spectrum (red is difficult) may be lacking.
Lumens are officially read at 555 nanometers, very green. This reading has nothing whatever to do with what color the rest of the LED diodes are emitting or what phosphors are active in flourescent lighting, all is dependent on the mix the manufacturers used.

Technology moves faster than peoples reaction to it. HPS at one time was the only discharge light available that would grow plants at all (1960's) so it became the standard. When multivapor lamps were introduced in the 1990's they were ignored as visually they resembled the Mercury discharge street lights that would kill plants.
However, the new lights were vastly superior but very very slow to catch on. Now technology has come full circle and the sun's spectrum can not only be matched, but improved upon.

But lumen meters became useless when the incandescent light became outmoded.

With a full spectrum light (not a tricolor fluorescent which has large gaps in its output) about 900 to a 1000 umol (photon count) is optimum. This is about half of what the sun puts out at noon.
The sun runs from 1 percent at dawn to 100 percent at noon and back to 1 percent at dusk. Full noon strength all day is not beneficial at all.

New cameras have a color balance screen which can be used for a spectrum graph, not sure if phone cameras have this. But if so then a PAR meter is in your hands.

Loc Dog · Dec 8, 2017

Thanks for the excellent explanation of why everyone tell me to use PAR meter. I do not even own a cell phone and camera is 15 years old. I wish there was somewhere I could rent a PAR meter, since I need it once, and would never need again. That is why I do not want to spend $300.

Loc Dog · Dec 8, 2017

I am going to hit up the manufacturer, to see if the have PAR charts based on distance from COB and watts running through it.

burmese · Dec 8, 2017

for hps, mh,cfl works best 40-50 000 lumens for 1m2,//waste of energy much higher//.
for special color leds lumens doesnt play role so you calculate rather with watt per square foot, or m2
//20w high quality led for square foot up to 50w with less quality led//.
also keep tops relatively still at the same length from lights and remember the stronger light is not always best for plant //they need light but also guards against light//

Loc Dog · Dec 8, 2017

burmese said:
for hps, mh,cfl works best 40-50 000 lumens for 1m2,//waste of energy much higher//.
for special color leds lumens doesnt play role so you calculate rather with watt per square foot, or m2
//20w high quality led for square foot up to 50w with less quality led//.
also keep tops relatively still at the same length from lights and remember the stronger light is not always best for plant //they need light but also guards against light//

I am going to trim over next few days, but yield is probably half or less than with HPS, but almost no leaf on buds that look awesome, and taste great. Was up 28 hours straight when I tried, so not sure how strong, since exhausted. I sent bridgelux an e-mail asking for PAR at 6", 12", 18" and 24" running 100 watts.

Loc Dog · Dec 8, 2017

Phaeton said:
Lumens became the standard of light units back when incandescent lighting was the only choice.
The percentage of green emitted by a hot metal filament was known and the total light could be calculated.
Now the light is emitted by specific mixed phosphors, each with its own specific color. How they are blended determines the spectrum graph.
If no green phosphors are included the lumen count will be nonexistent or very low. If green emitting phosphors are in the majority (residential lighting) then the lumen count will be high but the rest of the spectrum (red is difficult) may be lacking.
Lumens are officially read at 555 nanometers, very green. This reading has nothing whatever to do with what color the rest of the LED diodes are emitting or what phosphors are active in flourescent lighting, all is dependent on the mix the manufacturers used.

Technology moves faster than peoples reaction to it. HPS at one time was the only discharge light available that would grow plants at all (1960's) so it became the standard. When multivapor lamps were introduced in the 1990's they were ignored as visually they resembled the Mercury discharge street lights that would kill plants.
However, the new lights were vastly superior but very very slow to catch on. Now technology has come full circle and the sun's spectrum can not only be matched, but improved upon.

But lumen meters became useless when the incandescent light became outmoded.

With a full spectrum light (not a tricolor fluorescent which has large gaps in its output) about 900 to a 1000 umol (photon count) is optimum. This is about half of what the sun puts out at noon.
The sun runs from 1 percent at dawn to 100 percent at noon and back to 1 percent at dusk. Full noon strength all day is not beneficial at all.

New cameras have a color balance screen which can be used for a spectrum graph, not sure if phone cameras have this. But if so then a PAR meter is in your hands.

Do umols go down the further from light? I was told my setup should be putting out 800 umols, but they did not specify at what distance.

Phaeton · Dec 10, 2017

Loc Dog said:
Do umols go down the further from light? I was told my setup should be putting out 800 umols, but they did not specify at what distance.

The umol fall off depends on the beam angle, a 60 degree width has a one to one fall off, double the distance is half the intensity.
A 120 degree angle doubles the loss, at twice the distance only one fourth the light intensity hits the plants.

A bare bulb is the worst, double the distance and get one eighth the photon density. LEDs can hold a tighter focus than HID hoods, but many manufacturers us 120 or wider beams so they can claim larger footprints. This is a lose lose scenario, underlit plants underperform.
Some brands have a thirty degree beam and must be almost three feet above the plant to avoid hot spotting. The brands that get the best reviews run from 60 to 90 degree angles as the best compromise between intensity and penetration.

Some brands show the footprint and intensity at various distances and all are extremely center weighted, physics is like that. Using multiple overlapping lights or side lighting matched to the overheads will balance the light over the whole plant and the lower buds will be firm.

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What is optimum number of lumens at tops?

Loc Dog

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Phaeton

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Loc Dog

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Loc Dog

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burmese

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Loc Dog

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Phaeton

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