PAR Meeter???

[Dbarnes]

Does anyone have one? I hooked up the new AIs and i would like to get one and test out where its at and where it eventually needs to be.

Thanks,
Derek

 

[lpsouth1978@msn.com]

I have one you could use, but I am in Aurora.

 

[Heffe01]

Do par meters work on LEDs. Been a lot of talk about them not picking up the right spectrums.

 

[chrislorentz]

Dont believe so not accurate.

 

[Heffe01]

Think your looking for a quantum lux meter.

 

[lpsouth1978@msn.com]

It is my understanding that the PAR meter will not accurately measure the PAR of the blue LED's we use. Although it is not as accurate we can still get a general idea of what our LED's are capable of. I have seen it recommended to add 10-20% to the readings when using LED's. I generally split the difference and add 15%.

 

[Heffe01]

The Par meter cut the reading of my LEDs by 60%. That's why I was asking. But I wasn't sure of the quality of the meter that I used. Might have been bad as it looked old. Other tests I saw where up in the 1000+ range. Mine was reading 400 tops. But they were also using lux meters I think.

 

[Heffe01]

A lot of LEDs also use a 2:1 ratio of blue to white...so that about 60% in questionable coverage.

 

[lpsouth1978@msn.com]

The trouble with LUX meters is that a light may have high LUX while producing very little par. Also LUX does not convert well to PAR. It simply measures brightness without regard to the usable photosynthetic light.

 

[KhensuRa]

holy cow add 10% to 20% to led readings, no wonder I have to put most my stuff in the sand.

 

[Heffe01]

Kinda a catch 22 then. Sounds like par meter won't work due to the blue LEDs. And if what you say about a lux meter is true then it won't be accurate as well. Corals use the blue spectrum to grow, while white is only used to make it look more appealing to us.

 

[Heffe01]

It may be a whole lot more than 10-20%. Those are just best guesses...not proven fact yet. It all depends on your blue spectrum.

 

[lpsouth1978@msn.com]

I agree, there is no way currently for us to measure PAR when using LED's. There has been some talk that Apogee is working on a PAR meter that will, much more accurately, give PAR values for LED lighting. I am sure that this is because of the reefing world and our obsession with LED lighting.

Until that happens, I will still use my par meter and add 15%, if only because there is no better option right now.

 

[Heffe01]

Would you mind testing mine out sometime? Would be curious as to what another PAR meter quotes it at.

 

[lpsouth1978@msn.com]

I would be happy to. I only live a few minutes from you so I could do it just about any time. I would even be available this afternoon fro a while.

 

[Heffe01]

This afternoon works for me. Pm sent.

 

[Crit21]

The accuracy of the PAR readings depends on the meter you're using. Li-Cor meters are considered to be the gold standard, and provide a fairly accurate reading across the visible spectrum. The Apogee meters are terrible below 500nm, and don't read above 650nm (red) at all (I advise against red supplementation anyway). With the Apogee, if you measure one wavelength of LED at a time you can come pretty close if you only have one wavelength turned on at a time. If you have a cool white, you're still underestimating actual PAR. Using the conversion table below, all you have to do is multiply the blue/violet LED's PAR reading by the corresponding multiplier and you'll get pretty close to the real PAR.

Wavelength
Multiuply the Apogee reading by

400
3.3

410
2.5

420
2

430
1.6

440
1.4

450
1.25

460
1.2

470
1.1

480
1.1

 

[Cherub]

I wouldn't mind a par reading under the new lights