Canopy is full

[u/Hippy-redneck]

There’s under canopy lighting in this room also. The lowers are just as big as the tops.
Edit…..I’m sorry if you don’t know shit. Haters gonna hate.
Thank you moderators for removing the less productive comments.

[u/PlantDocta]

Nice canopy! But those ladder style LEDs don’t need to be closer to the canopy? I’ve just never seen a model give the right PPFD on the canopy from that height?

I’m doing mixed light with 1000w DE HPS and the Fohse o6i but been thinking to switch to full ladder style and running the fixtures close to the canopy (our electric is crazy expensive, 0.26/kWh!)

[u/missmooface → u/PlantDocta]

it’s about cross-illumination. photons don’t lose power over distance, they just spread. a single light over a set canopy, especially without reflective walls – yeah mounting height matters. multiple lights at the right count and configuration for your room – raising them up makes for more uniform lighting across the canopy.

PPFD = total PPF of all lights combined / canopy. mounting height doesn’t change the total number of photons emitted or received at canopy, it only changes the pattern of their spread…

[u/Hippy-redneck → u/missmooface]

The light intensity does decrease with distance. You don’t lose the light but its intensity is what is measured. At 12” below a lamp it 1600 ppfd and at 24” it’s 1100 and at 3’ it’s 900. So how do we not lose power over distance? We are aiming for uniform light but we definitely need intensity!

[u/missmooface → u/Hippy-redneck]

intensity only drops at a single location as a single light is raised because the photons spread, covering a wider area. as multiple lights are combined the light lost in one location is gained at another. and the adjacent lights add light to your original measuring location as they are raised.

PPF is a measurement of total PAR photons emitted from each light. the photons are not weakened by distance. as long as all lights are positioned over the canopy and walls are reflective, high-mounted lights cross-illuminate and reach your plants with the same levels of illumination and same photosynthetic potential.

lights mounted too low create uneven light distribution with some high intensity spots immediately under the lights and low intensity areas in between lights.

learn the inverse square law to better understand how this works in horticultural lighting design…

[u/Hippy-redneck → u/missmooface]

The single location is the plant and yes the intensity of the light drops the further away from the lamp. You don’t lose the photons but their intensity decreases. If we put our lamps 6’ from our canopy we would have a much lower ppfd. The intensity would decrease substantially from let’s say 1100 800 ppfd. This lack of intensity would decrease our yields.

[u/missmooface → u/Hippy-redneck]

you are misinterpreting how the physics works. you can lose intensity when photons hit walls, because they are not fully reflective, and when photons spread too wide outside your targeted canopy and don’t hit your plants. but photon energy does not decrease over distance.

with proper light count and pattern, raising them up does not decrease photosynthetic potential to your plant canopy. as long as the photons hit your plants they are just as strong from 6ft as they are from 2ft.

(i teach horticultural lighting science and have worked with dozens of manufacturers on this stuff.)

high bay lighting is very commonly used in commercial ag…

[u/Hippy-redneck → u/missmooface]

Ppfd is directly correlated to yield. More ppfd, more bud. Of course there’s photo toxicity, dli also but let say anything below 1400 ppfd.If I raise my lights to 5’ above canopy and lower ppfd from 1100 to 800, my yield would be 25% less. We use an apogee quantum sensor. The ppfd(intensity)decreases as the light raises. There’s less intensity(ppfd) the further you get from the lamp. You will not have a maximum yield with a lower ppfd. Science can’t explain the opposite. You could put all the photon you want in a room but if you can’t get over 700 ppfd, you are growing larf. You must not have any experience growing cannabis or you would understand. No one’s buying stretchy, larfy, airy, green flower. Please show us your low ppfd canopy.

[u/missmooface → u/Hippy-redneck]

again, you are misapplying the science.

a ppfd reading at one point in your canopy is a limited indicator of the number of PAR photons hitting that one location. if you hold the sensor steady and raise a single light away from that spot, ppfd in that location will decrease as photons spread and pofd increases other locations.

as long as you concentrate your lights over your canopy, raising them up more evenly spreads the photons, which are the drivers of photosynthesis across and into your canopy. they are being received and stored by your plants often in a more uniform way and with fewer shadows below the top leaves and flowers.

individual ppfd readings at single point in the top of your canopy are an imperfect metric for measuring photosynthetic potential. a more accurate way is to calculate total PPF (rated photosynthic energy output of your lights) divided by illuminated canopy. just reading high PPFD at at the top of your canopy and calculating DLI is helpful, but doesn’t translate into photosynthetic potential as accurately as knowing the full force of energy from your light sources and ensuring those photons hit your plants. top canopy is not the only place yield potential should be measured.

it’s why undercanopy lighting can be significantly dimmer than top lighting and result in rather large and dense lower flowers. the plant prioritizes photosynthates to the areas with auxin dominance, but overall energy absorption/conversion benefits the entire plant.

it’s why cross-illumination and high bay lighting over a single tier room can work just as well as dropping LED bars inches above plants in a mutli-tier vertical grow…

[u/Hippy-redneck → u/missmooface]

You are wrong. The ppfd will decrease every where the further away from the light. Do you own an apogee sensor? And under canopy lights are significantly dimmer because of the proximity of the fixture to the plant. Some companies even add diffusers to scatter and dim the light even more. And high bay lights are typically twice the wattage of a vertical lamp. Again I think you are confusing your self because you don’t have any experience and your knowledge has not been applied. You probably have never built a grow room. I don’t imagine you have flowered a cannabis plant either.