PAR meter info needed please..

[pepperdust]

Hi guys,

I wanted to check to make sure I was correct.. on a PAR meter, if you have a green LED it will show whatever number right? then if I add say 2 green LED the meter will read a higher PAR correct?

someone was getting me confused saying: "par meters measure in umole/s (micromoles). if there is too much green the umole/s reading will be lower. an all green panel will measure at the lowest par rating. ana all green panel will measure at the highest lumens though"

so who's right, the guy with the quote or what I said in the beginning?

 

[SemiMan]

Hi guys,

I wanted to check to make sure I was correct.. on a PAR meter, if you have a green LED it will show whatever number right? then if I add say 2 green LED the meter will read a higher PAR correct?

someone was getting me confused saying: "par meters measure in umole/s (micromoles). if there is too much green the umole/s reading will be lower. an all green panel will measure at the lowest par rating. ana all green panel will measure at the highest lumens though"

so who's right, the guy with the quote or what I said in the beginning?

You are both right, you are just misunderstanding the quote. The quote is about relative amount of green. With a higher relative amount of green, the PAR readings (in theory) will be lower, compared to a similar device where more light is outside green.

And similar, if you only have green, the output is relative to how much total there is.

Of course, this is all a good theory, but reality is that PAR meters only approximate actual PAR. Some meters, i.e. Light Scout greatly enhance the red, while having little response in blue. Apogee meters are a lot flatter, but they measure pretty flat from green to red, when they should be lower in the red.

Of course, then there are all the theories, research, etc. that PAR is only a part of what drivers plant growth as photosynthesis is just one process in plant growth.

Semiman