PPDF/DLI and multiple LED lights

[mystcl]

Hi,

I'm a bit stuck with calculations of my PPDF/DLI levels since i'm using multiple LED lights in grow box.

So, I have one LED light above 2 plants and then another LED light next to it, above the other two plants.
In total, there are 4 plants and 2 LED lights (spiderfarmer sf1000 100w)

My first two plants (left ones) are a bit behind and they need lower PPDF than other two plants (right ones).
The first LED light is set to provide 200 PPDF on left plants surface while second LED light is set to provide 300 PPDF on surface of two other plants.

Problem is that first LED light is providing additional PPDF to the second set of plants and second LED light is providing additional PPDF to first set of plants.

How do I calculate total PPDF/DLI each plant is receiving?

Thanks!

 

[Lil Dab]

Have you tried the Photone app? It’s a par meter app for your smart phone

 

[mystcl]

Have you tried the Photone app? It’s a par meter app for your smart phone

yes, im using it to measure. Some people say it's not that accurate, though.

Do you know if i need to add multiple values from multiple light sources to have my final PPDF level for each plant?

 

[Lil Dab]

yes, im using it to measure. Some people say it's not that accurate, though.

Do you know if i need to add multiple values from multiple light sources to have my final PPDF level for each plant?

Everything I’ve seen from my personal experience and others here it’s plenty close enough for what we are doing.

No I don’t know I assume no and you should see a rise and lower in ppfd if you raise or lower one of the lights. It’s probably going to take some experimenting to find the sweet spot

 

[Cobstopper]

Do you know if i need to add multiple values from multiple light sources to have my final PPDF level for each plant?

No need to add multiple values. As you move your phone around you’ll see the numbers change. Just need to experiment like Dab said.
I use the DLI chart below with the Photone app
and get great results. Only thing for me is I grow organic and can’t go much over 30 during flower without causing detriment to the plants.
Others here get to mid 40’s with no issues so just a heads up.

 

[Delps8]

No need to add multiple values. As you move your phone around you’ll see the numbers change. Just need to experiment like Dab said.
I use the DLI chart below with the Photone app
and get great results. Only thing for me is I grow organic and can’t go much over 30 during flower without causing detriment to the plants.
Others here get to mid 40’s with no issues so just a heads up.

And others grow their autos with DLI's in the 80's.

Cannabis will grow at light levels between 64µmol ("the light compensation point") with a "light saturation point" of about 1100µmol in ambient CO2. The LSP varies from strain to strain and I know that the 1100 value is attainable because that's about the max where I end up with my plants.

Cannabis is an unusual plant in that crop yield increases in a linear/an almost manner as light levels increase.The table below is from research where yield was not quite linear.

Per the table, a crop grown at an average PPFD of, say, 700µmol will be about 25% smaller than a crop grown at 1000µmol.

Again, there's no harm in following the graphic because cannabis will do just fine but, all other things being equal, you will have a larger crop if you disregard it and feed your plants well (light is food to a plant).

 

[Delps8]

Hi,

I'm a bit stuck with calculations of my PPDF/DLI levels since i'm using multiple LED lights in grow box.

So, I have one LED light above 2 plants and then another LED light next to it, above the other two plants.
In total, there are 4 plants and 2 LED lights (spiderfarmer sf1000 100w)

My first two plants (left ones) are a bit behind and they need lower PPDF than other two plants (right ones).
The first LED light is set to provide 200 PPDF on left plants surface while second LED light is set to provide 300 PPDF on surface of two other plants.

Problem is that first LED light is providing additional PPDF to the second set of plants and second LED light is providing additional PPDF to first set of plants.

How do I calculate total PPDF/DLI each plant is receiving?

Thanks!

If you're on an iPhone, are you using a diffuser?

"My first two plants (left ones) are a bit behind and they need lower PPDF than other two plants (right ones)."
No, don't do that. It's not unusual for growers to think that it's good to turn a light down if they perceive something is "wrong" with a plant. Almost without exception, that will not resolve the issue. Light is how a plant makes food. Less light = less food = slower growth or slower recovery.

Also, rather than trying to calculate PPFD (which is, in practical terms, impossible) why not just use your light meter?