PPFD and distance

[marzig]

With ppfd being equal, is there any disadvantage to having led lights farther from the canopy?

 

[amneziaHaze]

Unless you are in a frezzing room no.it should be cooler at bigger distance

 

[Rocket Soul]

Its an advantage to have them further away if ppfd stays the same; less heat radiated from the light towards cannopy (though this is relative, some situations you want the radiated heat) and more space to move air over the cannopy, easier access...

Edit to amend: there is no real negative in having higher hanging height but theres a negative in needing higher hanging height. Also, in practice theres always height limitations, be it in a tent or an open space: the taller you can grow your plant the thicker your main stem, the more it can drink and the more buds it can grow. Also in an open space the higher you have to hang your light the more of the light is lost to walls, but generally in a tent with reflective walls you dont have as much loss. As long as your hanging height doesnt affect the space you got reserved for plant growth the higher it is the better, ppfd being the same, but this is a very theoretical situation that generally never happens unless your wasting some watts.

 

[Hook Daddy]

If ppfd is equal, the higher the light the bigger the footprint covered by the light as well.

 

[Frankindank]

We all need more detail on the fixtures to make educated statements.

What is the PPF of th fixtures? If not available what are the wattages?
Any optics involved? Same on each fixture?
Same physical size fixtures?
Spectrums the same?

All matters to what is the differences in potential results of higher or lower hanging fixtures could be.

PPF and PPFD are not interchangeable and both matter in this situation.

 

[marzig]

We all need more detail on the fixtures to make educated statements.

What is the PPF of th fixtures? If not available what are the wattages?
Any optics involved? Same on each fixture?
Same physical size fixtures?
Spectrums the same?

All matters to what is the differences in potential results of higher or lower hanging fixtures could be.

PPF and PPFD are not interchangeable and both matter in this situation.

I was just curious in general terms.

 

[Roy O'Bannon]

Maybe if you needed more heat on your plant.
I seem to have to balance height, par and leaf temp. I try to keep the -5 f for good vpd numbers.

 

[marzig]

Its an advantage to have them further away if ppfd stays the same; less heat radiated from the light towards cannopy (though this is relative, some situations you want the radiated heat) and more space to move air over the cannopy, easier access...

Edit to amend: there is no real negative in having higher hanging height but theres a negative in needing higher hanging height. Also, in practice theres always height limitations, be it in a tent or an open space: the taller you can grow your plant the thicker your main stem, the more it can drink and the more buds it can grow. Also in an open space the higher you have to hang your light the more of the light is lost to walls, but generally in a tent with reflective walls you dont have as much loss. As long as your hanging height doesnt affect the space you got reserved for plant growth the higher it is the better, ppfd being the same, but this is a very theoretical situation that generally never happens unless your wasting some watts.

I'm in a small tent so no concern with loss. In the early part of this grow, so room for height isn't an issue for now.

 

[marzig]

If ppfd is equal, the higher the light the bigger the footprint covered by the light as well.

I like the idea of a larger foot print.

 

[marzig]

Maybe if you needed more heat on your plant.
I seem to have to balance height, par and leaf temp. I try to keep the -5 f for good vpd numbers.

No concerns with temps, I just prefer to adjust intensity rather than raise and lower fixtures for as long as possible