PPFD

[Ganjier]

I am using a PPFD app on my phone. I am 2 weeks in flower. My mars Hydro FC 4800 led is about 15" from canopy in my 3x3 tent. i am running at 60% power. PPFD on phone app is showing 490. If I blast the light to 100% I get 1000 at this distance. Is 490 too low? Should I increase to like 700? Not sure how accurate it is.

 

[Lesso]

1000 is the most you can use without co2.
490 is low. That's seedling and early veg strength.

 

[oldfogey8]

I agree with lesso that 490 is low. I have read though that 1500-1700 is the most plants can use without CO2 supplementation meaning more will not be useful to the plants. I don’t have a PPFD meter/app nor have I done any experiments to prove or disprove the 1500-1700 numbers. Another metric I have been reading about is DLI(daily lighting integral) which sums the PPFD over time with lights on. I think @T_Dub is using DLI in his mad scientist grow now. All that gobbledygook said, I would gradually increase the light output and keep an eye on the plants for signs of light stress.

I can’t for the life of me find any scientific papers this morning where PPFD or DLI are examined. I think the bud I smoked last night fkd up my search skills. Maybe too much PPFD…

 

[WeedHopper]

I must have been doing it all wrong all these yrs. Never checked PPFD.
Oh wait,,,I lied,,I used the back of my hand.

 

[Lesso]

I agree with lesso that 490 is low. I have read though that 1500-1700 is the most plants can use without CO2 supplementation meaning more will not be useful to the plants. I don’t have a PPFD meter/app nor have I done any experiments to prove or disprove the 1500-1700 numbers. Another metric I have been reading about is DLI(daily lighting integral) which sums the PPFD over time with lights on. I think @T_Dub is using DLI in his mad scientist grow now. All that gobbledygook said, I would gradually increase the light output and keep an eye on the plants for signs of light stress.

I can’t for the life of me find any scientific papers this morning where PPFD or DLI are examined. I think the bud I smoked last night fkd up my search skills. Maybe too much PPFD…

They can use higher than 1000 but there is a big drop with diminishing returns.

 

[oldfogey8]

They can use higher than 1000 but there is a big drop with diminishing returns.

There has to be. Solar panels and leaves both take photons and convert them into energy but like a bucket of water can only use some percentage of the light.

 

[oldfogey8]

I must have been doing it all wrong all these yrs. Never checked PPFD.
Oh wait,,,I lied,,I used the back of my hand.

PPFD=Pigment Produced From Difracted(Light)

 

[T_Dub]

I am using a PPFD app on my phone. I am 2 weeks in flower. My mars Hydro FC 4800 led is about 15" from canopy in my 3x3 tent. i am running at 60% power. PPFD on phone app is showing 490. If I blast the light to 100% I get 1000 at this distance. Is 490 too low? Should I increase to like 700? Not sure how accurate it is.

I’m still learning about ideal lighting. I’ve been following the advice of the Photone light measuring app. It required several different Apple devices and multiple paper choices ( paper is used as a diffuser over your camera) before I came up with an accurate reading. My readings were wildly different using several Apple devices and different paper thicknesses. I’ve settled on using my iPad mini and 22 pound white paper as the diffuser. I’ve verified the lighting against a lux meter to get some degree of validation.

You don’t mention the app or phone that you are using, but there are some differences in accuracy. Here’s a video on the different apps. The Photone app was the most accurate.



Based on the Photone app cannabis guide, you want your ppfd between 500 and 1050. Looking at your ppfd map for your lamp, it looks like it covers a 3x3 well within those ppfd goals at 12” above the canopy, and you can even go as low as 10” it says without going over the ppfd targets.

So I’d probably start slowly lowering your lights and raising your intensity…all while watching the leaves for any signs of stress.

I can only go off those two sources.

I’m two weeks into flower and running closer to 1050-1200 ppfd with no light stress so far.

Hope that helps….

 

[WeedHopper]

Nope didn't help me at all.

 

[oldfogey8]

Nope didn't help me at all.

Kinda hard to turn up the sun or lower it closer to the plants…

 

[Ganjier]

Now my head hurts.

 

[oldfogey8]

Now my head hurts.

Smoke some weed. That usually helps …

 

[Necromancer]

This is what I go by roughly for ppfd as my plants grow
Seedling 150
Early Veg 300
Veg 500
Transition 600
Early Flower 700
Flowering 850
Late Flowering 600

 

[ilv911]

Matching app numbers with your lights is crucial. Every famous led got its own ppfd map or a review on youtube with ppfd numbers so you can fix app's numbers

 

[Bubba]

They can use higher than 1000 but there is a big drop with diminishing returns.

Yup. I find that after 1000 or so many strains freak out. Not so much burn, but more light make plant process more food/nutes. Problem is, they can only soak up and use so much. Once that's past, Co2 needed. I've never used Co2 , run lights based on plants reaction. At flower, some soak up 100%. Some I have to turn back to 80%.

Bubba

 

[Bubba]

Kinda hard to turn up the sun or lower it closer to the plants…

But what a PAR map!

Bubba

 

[pute]

Now I have a headache!

 

[ilv911]

Yup. I find that after 1000 or so many strains freak out. Not so much burn, but more light make plant process more food/nutes. Problem is, they can only soak up and use so much. Once that's past, Co2 needed. I've never used Co2 , run lights based on plants reaction. At flower, some soak up 100%. Some I have to turn back to 80%.

Bubba

Yup.. my white widow could stand maximum 900ppfd with amnesia haze now on 1000ppfd without problem but fks up my vpd so .. 900ppfd too

 

[user 64919]

I shoot for 900.

 

[pute]

My plants tell me everything I need to know.