PAR #'s

[xabo]

Is PAR PAR? What I'm asking is, are the PAR# we get from MH the same as LED? Say I'm getting PAR 300 for MH and the same for LED. While they are different lighting systems, delivering light in different means (I'm guessing) do the numbers equate?

I apologize in advance if this is a dumb/crazy question.

 

[madweazl]

Provided the light being measured is between 400-700nm, yes. Some meters are better than others but something like Apogee's "full spectrum" sensor is fairly accurate in this range.

 

[A. grandis]

... and both the metal halides and LEDs have spectrum beyond the 700nm.
Some say that's not used by the corals and some others say that is.
Quality of spectrum and distribution of that spectrum is more important than PAR alone.
That is the efficacy of a light source for that particular application.
UV from metal halides can't be compared to any LED available for aquarium use today.
It's just impossible to reproduce the UV emitted by the halides with LEDs in practical terms, said Mr. Tullio Del Aquila.
UV is important for coral metabolism. That's why LED companies are trying to sell their UV bulbs in some of the fixtures.
The distribution of a nice metal halide fixture will offer a vast coverage embracing the tank and the LEDs won't do the same.
Should we consider PAR and forget the rest?
This isn't any fire on LEDs, but to remind us and teach the newbies that PAR alone isn't to be considered when measuring different artificial light sources.
That's how I see.
Grandis.

 

[USMC 4 LIFE]

... and both the metal halides and LEDs have spectrum beyond the 700nm.
Some say that's not used by the corals and some others say that is.
Quality of spectrum and distribution of that spectrum is more important than PAR alone.
That is the efficacy of a light source for that particular application.
UV from metal halides can't be compared to any LED available for aquarium use today.
It's just impossible to reproduce the UV emitted by the halides with LEDs in practical terms, said Mr. Tullio Del Aquila.
UV is important for coral metabolism. That's why LED companies are trying to sell their UV bulbs in some of the fixtures.
The distribution of a nice metal halide fixture will offer a vast coverage embracing the tank and the LEDs won't do the same.
Should we consider PAR and forget the rest?
This isn't any fire on LEDs, but to remind us and teach the newbies that PAR alone isn't to be considered when measuring different artificial light sources.
That's how I see.
Grandis.[/

 

[jda]

Most PAR meters will not get much blue below 440 and it tapers off. They capture more LED output than T5 and especially MH. If you get the same number from a Radion as you do a Radium, you can bet that the Radium has more output than the Radion... spectrum from 350 to about 850 has benefit and the Radium has that and the Radion is mostly in the visible range.

Then, you have to take spread into account. A very powerful MH might have the same PAR as a LED, but it might be pretty constant over a 24x24 area instead of just a peak directly under the diodes.

The tricky thing is that you have kinda have to look at a MH or T5 chart and guess at how much more. Some bulbs with massive amounts of output below 440 and especially below 420, and then again above 680, could be 20-40%, or more.

 

[oreo54]

What "the best" PAR meter measures:

note old article..
https://www.advancedaquarist.com/2012/10/aafeature

 

[mcarroll]

While they are different lighting systems, delivering light in different means (I'm guessing) do the numbers equate?

I think if you understand what PAR is (and is not) it will help.

You also have to define what you mean by "equate".

PAR is an average of sorts and measures power between 400-700nm.

It tells you nothing about power of a particular wavelength or about overall color, etc.

So to the extent that you care about power delivery within the range that PAR measures, they equate.

To the extent you care about color or power in a given wavelength, there's no info there for you at all.​

(Plants and corals seem to care about light frequency and numbers of photons....something to keep in mind since neither is being reported with PAR. I still measure with a lux meter, which also does not report frequency or number of photons. )

 

[oreo54]

PAR is just a misused term.
It is just the def of the accepted usable light range for photosynthesis.
There is no PAR of "30" so to speak...There is just PAR and if you add "30" becomes PPF..or PPFD

Apogee/Li-cor does not sell a "PAR" meter.nobody does.. Doesn't exist.. Can't..

All of them translate photon strikes to electrical impulses..
So yes you measure photons .........
https://www.ledgrowlightsdepot.com/pages/par-ppf-ppfd-and-dli-uncovered

At least this is about how I understand it..

May take years to correct..

 

[mcarroll]

PAR is just a misused term.

The fun part. anyone can look it up on Wikipedia or go read some industry articles to read how it's used. But if you ask 100 reefers exactly what PAR is I think we would get 100 different answers.

I don't think too many people know what PAR means. And as I said, I still use a lux meter.

 

[saltyfilmfolks]

PAR is just a misused term.
It is just the def of the accepted usable light range for photosynthesis.
There is no PAR of "30" so to speak...There is just PAR and if you add "30" becomes PPF..or PPFD

Apogee/Li-cor does not sell a "PAR" meter.nobody does.. Doesn't exist.. Can't..

All of them translate photon strikes to electrical impulses..
So yes you measure photons .........
https://www.ledgrowlightsdepot.com/pages/par-ppf-ppfd-and-dli-uncovered

At least this is about how I understand it..

May take years to correct..

This is correct. For most , hard to understand.

For the op , simply put, no, different colors are different par , as you can change spectrum. So a 56k halide and a Radion led running mostly blue will have different attributes at the same par number.

The concept of pur comes into play. As pur is what is useful to the organism. Like coral VS algaes needs , what is useful is different from organism to organism.

 

[oreo54]

The fun part. anyone can look it up on Wikipedia or go read some industry articles to read how it's used. But if you ask 100 reefers exactly what PAR is I think we would get 100 different answers.

I don't think too many people know what PAR means. And as I said, I still use a lux meter.

Yea most understand what is implied though.. So there is that going for it......
PAR is easier to say than "pfffffddd"..

 

[oreo54]

This is correct. For most , hard to understand.

For the op , simply put, no, different colors are different par , as you can change spectrum. So a 56k halide and a Radion led running mostly blue will have different attributes at the same par number.

The concept of pur comes into play. As pur is what is useful to the organism. Like coral VS algaes needs , what is useful is different from organism to organism.

Going to get REAL anal here:
different "colors" are not different PAR..

PAR is a definition.. Defined by radiation from 400-70nm..
BY definition all wavelengths are treated equally..

400nm is the same PAR as 55onm...
Yes possibly not the same PUR (should it be PPFD based on the def (or set, or weighted by) of PUR?)

REALLY splitting hairs here..I apologize..

PAR is a defined subset of the electromatic spectrum, PUR is a subset of PAR (w/ possible additions, like 380 820 ect.) as is "set" of radiation quantified by Lumens.

more I write weirder it gets...

 

[saltyfilmfolks]

Going to get REAL anal here:
different "colors" are not different PAR..

PAR is a definition.. Defined by radiation from 400-70nm..
BY definition all wavelengths are treated equally..

400nm is the same PAR as 55onm...
Yes possibly not the same PUR (should it be PPFD based on the def (or set, or weighted by) of PUR?)

REALLY splitting hairs here..I apologize..

PAR is a defined subset of the electromatic spectrum, PUR is a subset of PAR (w/ possible additions, like 380 820 ect.) as is "set" of radiation quantified by Lumens.

more I write weirder it gets...

You and me, we can split hairs. I’m down with that.
For most , it’s confusing and folks don’t belive meters work, Rather than understanding how they work.

Kinda like a Red Sea mag Test. Lol.

 

[Johniejumbo]

I thought par was the number of hits it’s supposed to take to complete a hole on the golf course. Man I have been so confused.

 

[xabo]

For the op , simply put, no, different colors are different par , as you can change spectrum. So a 56k halide and a Radion led running mostly blue will have different attributes at the same par number.

Kinda' what I was looking for. I've read that when switching from MH to LED, you want to the match PAR#'s.

 

[A. grandis]

This thread got very confusing now! LOL!
There are lots of different opinions about the spectrum/PAR/PUR useful areas of the charts out there.
What is really the truth? Are they personal opinions?
I get confused...
Grandis.

 

[A. grandis]

Kinda' what I was looking for. I've read that when switching from MH to LED, you want to the match PAR#'s.

But again, the MHs have different properties than LEDs with the fixtures's reflectors, allowing such distribution, and the UV... Not PAR alone.
Grandis.

 

[A. grandis]

You and me, we can split hairs. I’m down with that.
For most , it’s confusing and folks don’t belive meters work, Rather than understanding how they work.

Kinda like a Red Sea mag Test. Lol.

The meters also have their limitations, like they say...
Different models will allow different measurements. Some can be used for LEDs and others can't..
Mr. Tullio said they are mostly calibrated for T5s.. LOL!
Very confusing..
I think they can be used to compare the PAR of a same bulb to determinate when to be changed... that would be ok..
Salty: the more I try to understand reading articles and web sites, the more confused I become with the different opinions..LOL!
Grandis.

 

[mcarroll]

True. A lux meter can be used for the same purpose.

(lux would be analogous to PUR, fwiw)

Matching numbers with either type of meter does not imply the same wavelengths of color, it just implies a similar amount of power. What makes it work for us is that we are all measuring reef lights which are all pretty darn similar in their output.

Here's an example that won't work…

If you were switching to 20,000K halide from high-pressure sodium (HPS) lights and matched PAR or lux numbers to "ease the transition", your corals would still hate you because there are no wavelengths friendly to them in a high-pressure sodium bulb even though there's a ton of PAR in that HPS bulb.

scientists like par because it's agnostic to details like this and they can use it in power equations. I think practitioners generally prefer lux or PUR as those units take the application a bit more into account.

Check out the W page on PAR too...it's pretty darned good!
https://en.wikipedia.org/wiki/Photosynthetically_active_radiation?wprov=sfti1

 

[oreo54]

scientists like par because it's agnostic to details like this and they can use it in power equations

Well more so they are speaking the same "language" really..

It's a standard... and implies equal # of photons regardless of wavelength.
"PAR" (black rectangle lines rectangle) Lumens and ONE expression (species dependent, in this case an "average"of species.. McCree curve) of PUR...(or weighted "PAR" if you prefer)
When one converts Lumen measurements to "PAR" this includes assumptions as to the losses based on the measurement..
Every light will have a different conversion factor..Oddly it is pretty similar across many light types..
Just understand it (conversion factor) is an estimate..and has been checked, for accuracy, by many..

photosynthetic photon flux density (PPFD) in micromoles per second per square meter (μmol/s-m2) for the given light source. (over the range of 400-700nm or as defined, like 40PPFD for a 660nm light source)

PPF is just area-less
1 mole of photons = 6.022 x 1023 photons. 10 to the 23rd power..but load o photons
uMole 10 minus 6 of a mole.