Measuring Par?

[NanaReefer]

What is the best way to measure Par when using LED's? Is it true par meters are pretty much useless when it comes to LED's?

 

[fishmommy]

I have the Apogee meter and LEDs and to be honest the meter is IMO useless. I get really low readings while my corals bleach.

 

[TJ's Reef]

Putting this in 'layman's terms' the main reason any PAR meter is only a bit helpful at best is: they measure the full range of " photosynthetic active radiation " not PUR ( photosynthetic usable radiation) which is more defined. The advantage of using LED lighting is that we can be very specific to to particular ranges of the overall PAR spectrum targeting PUR numbers without much garbage light. This greatly affects the typical PAR meter reading. The so-called garbage light of the spectrum makes up much of the PAR numbers and lack of it with LED's skew these numbers down. So while a LED fixture may show only 75% of the desired PAR value in actuality may be producing 150% of the needed PUR values. The Blue end of the PAR/PUR range is the most overdone with LED's as the White emitters are also Blue heavy and are really just Blue emitters with a Phosphorus coating creating the White we see. Very hard to type on my little phone key pad so hopefully makes sense here, will edit if necessary when on my PC.

Cheers, Todd

 

[NanaReefer]

I really need to better understand my unit. Least one of us takes a trip out the window Any meter is not an option financially. So I figure, knowing how they work is a must.
What is the difference between a 3w Cool White Cree & a 3w Cool White Bridgelux? Are the differences really so big, making one better then the other?
Is it true that a 1-2 ratio is best, meaning for every 1 white 2 blues should be used?

 

[saltyphish]

following

 

[tigerdragon]

Brightness of light when it comes to led doesnt really mean anything you can have 400w of led pwr but not have any par value. That is why when you see light percentages on led the blues are usually higher than the whites. The blue spectrum has more of the beneficial wavelengths but there are some in the whites just have to watch how high you drive them take it easy when acclimating led is a much more focused light than t5 or halide

 

[ReefLEDLights]

What is the best way to measure Par when using LED's? Is it true par meters are pretty much useless when it comes to LED's?

PAR Meters do not give an exact reading here is a link explaining the errors PAR Meter Facts

That said a PAR Meter is extremely important when changing lights. A Before and After reading can be extremely useful in proper acclimation.

Our Fixtures and Kits are designed to provide far above the minimum light needed for Photosynthesis. In fact our latest Genesis Fixtures produce about twice the PAR of our competitor while consuming less electricity.

The right strong light will cause corals, especially SPS, to develop pigments to reflect this excessive light. This is why seasoned SPS owners prefer 400 watt MH over 250 watt MH

These pigments and proteins can change a boring brown colour coral into much more colourful one.

Corals use primarily the 400-500nm for photosynthesis, this generally makes LED fixtures brighter than advertised. We recommend starting 10% below your old PAR reading and work up from there.

Also a gradual sunrise and sunset is recommended with peak PAR only 4-6 hours a day.

Bill

 

[NanaReefer]

Why build them far above what is needed? Simply to change the corals natural color into something more desirable?

Without the use of a par meter, how will I know the proper placement for my Birds Nest. How long would it generally take for the color to show up? I was told if it didn't color up within 2wks then it's not getting the right light. Yet all my LPS look great. Again with the par factor right?

 

[ReefLEDLights]

Why build them far above what is needed? Simply to change the corals natural color into something more desirable?

Without the use of a par meter, how will I know the proper placement for my Birds Nest. How long would it generally take for the color to show up? I was told if it didn't color up within 2wks then it's not getting the right light. Yet all my LPS look great. Again with the par factor right?

Corals are very adaptable. In bright light they develop Proteins and Pigments to reflect the excessive light. These often cause the colours we want.

Depending on acclimation it can take a few weeks or months. Also the colour is dependent on pristine water quality. Each tank is different and frags from our EEs Tank look different in my tank...Lights are the same.

Without a Par Meter you can use a camera and note the exposure and f stop. Then adjust your LEDs to slightly below the same f stop and exposure reading....Its not scientific but brightness and PAR are somewhat linear in aquarium lighting.

Overall I like 200-300 PAR on the sand Bed. This allows for carpet anemones and clams.

Bill

 

[NanaReefer]

And what type of camera would this require? I'm guessing something more then my iPhone, iPad or my Canon Powershot? Lol

 

[g6gang]

Corals are very adaptable. In bright light they develop Proteins and Pigments to reflect the excessive light. These often cause the colours we want.

Depending on acclimation it can take a few weeks or months. Also the colour is dependent on pristine water quality. Each tank is different and frags from our EEs Tank look different in my tank...Lights are the same.

Without a Par Meter you can use a camera and note the exposure and f stop. Then adjust your LEDs to slightly below the same f stop and exposure reading....Its not scientific but brightness and PAR are somewhat linear in aquarium lighting.

Overall I like 200-300 PAR on the sand Bed. This allows for carpet anemones and clams.

Bill

Wow this is very interesting method I never considered. Can you please expand? I am going from a low end LED to "I think" a higher end full spectrum LED, so I basically want to make sure I switch the lights with the same intensity and then gradually increase. I don;t really care what the PAR values will be (as long as corals are happy I dont care about the #). What I do care about is putting them into shock.

So would I do the following:

1) Have no other lighting in room (say shut shades, lights etc)
2) Put camera in auto focus mode and poingt to same location for before and after (maybe put cam on tripod)
3) make note of current intensity on existing LED
4) Take picture and note exposure and f.stop
5) Replace with new lights (set to an intensity that would like to start with)
6) Take picture with same camera settings, location and other ambient light
7) Note exposer and f.stop

How would you know what to do comparing the numbers? When you say exposure are you talking about ISO, shutter speed or both?

Thanks for the tip - I was on the search for par meter, but I do have a Nikon DSLR - not trying to be exact, but want to feel warm and fuzzy that I have the lights tuned to as close to what corals were getting before. Even though I am going LED -> LED I want to be extrac careful - I killed most of my tank in past when replacing all my T5 HO bulbs at once

 

[ReefLEDLights]

The Human Eye has a hard time remembering intensity. A camera is more accurate in measuring intensity.

Note the same f stop exposure and iso and the intensity will be close.

Using intensity instead of an actual PAR reading will get you close when changing fixtures. Renting a PAR meter is a better option.

Some of the Cheap Generic LED Fixtures produce a decent amount of PAR others do not.

Bill

 

[David Engh]

Would a lux meter be an more helpful then the par meter? Is there a different method to use this than the other?

 

[ReefLEDLights]

Corals are Life...
Each is an animal who is dependent on captured food and or light
This is a very delicate enterprise
A LUX Meter V PAR Meter is a difference in measuring the light giving life...That said any change in light is stressful...Its best to minimize this this stress...

 

[saltyfilmfolks]

A lux meter measures intensity of light. A very useful thing. I talk about that a lot here and how it relates to par. IMO it's easier than a camera. Measure the intensity at the top of the water basically.
I did once here use a guys camera and settings and then with my camera and a light meter figure out how many foot candles he used to expose made Fc into lux then calculated his approx par.

Any way. Look at apogee website. They have a very good article on using their new par meter for led. Their new par meter is designed specifically for this. I think there's a new attachment.

 

[saltyfilmfolks]

Fwiw. 100,000 lux devide by 50(the sun) is 2000 par (Dana Riddle)
A Chinese black box is 63 at a w/b ratio of
1-1. ( my long comaritive research)

So a chi BB at 40000 lux is 634 par approx.
so increasing 2500 lux is approx 40 par.

 

[saltyfilmfolks]

Wow this is very interesting method I never considered. Can you please expand? I am going from a low end LED to "I think" a higher end full spectrum LED, so I basically want to make sure I switch the lights with the same intensity and then gradually increase. I don;t really care what the PAR values will be (as long as corals are happy I dont care about the #). What I do care about is putting them into shock.

So would I do the following:

1) Have no other lighting in room (say shut shades, lights etc)
2) Put camera in auto focus mode and poingt to same location for before and after (maybe put cam on tripod)
3) make note of current intensity on existing LED
4) Take picture and note exposure and f.stop
5) Replace with new lights (set to an intensity that would like to start with)
6) Take picture with same camera settings, location and other ambient light
7) Note exposer and f.stop

How would you know what to do comparing the numbers? When you say exposure are you talking about ISO, shutter speed or both?

Thanks for the tip - I was on the search for par meter, but I do have a Nikon DSLR - not trying to be exact, but want to feel warm and fuzzy that I have the lights tuned to as close to what corals were getting before. Even though I am going LED -> LED I want to be extrac careful - I killed most of my tank in past when replacing all my T5 HO bulbs at once

lux meter and reduce 30% intensity from old fixture. fwiw an ati Coral + has insanely high par value(40? sorry it late and I dont have my chart)w low intensity
40000 lux / 40 = 1000 par

 

[saltyfilmfolks]

I really need to better understand my unit. Least one of us takes a trip out the window Any meter is not an option financially. So I figure, knowing how they work is a must.
What is the difference between a 3w Cool White Cree & a 3w Cool White Bridgelux? Are the differences really so big, making one better then the other?
Is it true that a 1-2 ratio is best, meaning for every 1 white 2 blues should be used?

Dont sweat those details. we should care less about how the watch works and more about what time it is.
A light at full on both channels has a specific color temp/ Led seem to land in the 14,000 to 16000 kelvin range. By lowering the white you increase the kelvin temp. Ie 20k like a radium halide. Or decrease the blue to 14l like a Phoenix 14k halide.

Brightness of light when it comes to led doesnt really mean anything you can have 400w of led pwr but not have any par value. That is why when you see light percentages on led the blues are usually higher than the whites. The blue spectrum has more of the beneficial wavelengths but there are some in the whites just have to watch how high you drive them take it easy when acclimating led is a much more focused light than t5 or halide

imo ime some of my corals DO prefer 14k kelvin over 20k kelvin. and fwiw generally your whites run 10000 kelvin to 14k anyway or a combination to achieve that number.
AND its not a true kelvin temp but that will get confusing
and all light has par value. weird right?
and if you can see the light it has lux intensity. more correctly, intensity that can be measured in lux.

 

[NanaReefer]

Dont sweat those details. we should care less about how the watch works and more about what time it is.
A light at full on both channels has a specific color temp/ Led seem to land in the 14,000 to 16000 kelvin range. By lowering the white you increase the kelvin temp. Ie 20k like a radium halide. Or decrease the blue to 14l like a Phoenix 14k halide.



imo ime some of my corals DO prefer 14k kelvin over 20k kelvin. and fwiw generally your whites run 10000 kelvin to 14k anyway or a combination to achieve that number.
AND its not a true kelvin temp but that will get confusing
and all light has par value. weird right?
and if you can see the light it has lux intensity. more correctly, intensity that can be measured in lux.

2yrs to late. But thanks anyways [emoji2]