LED PAR Readings

lynxvs · 02/02/2009, 09:51 PM

I recently upgraded my DIY LED light with the following and took some PAR readings:

A. Increased LED count to 60 vs 50.
B. Added two cyan LEDs
C. Upgraded LEDs to higher lumen bin.

I am using an Apogee Quantum Sensor model SQ-110. I have three sets of readings that I took on my 29 Gal. The LED light is 6" off the surface.

50 LEDs Royal Blue and Cool white Rebels
I measured the PAR on to of the eggcrate directly under one of the arrays and measured a PAR reading of 1450

60 LEDs Royal Blue, Cool White and Cyan with higher lumen bin
I measured the PAR on to of the eggcrate directly under one of the arrays and measured a PAR reading of 2150

Then I broke out my old 65 Watt CF and made some measurements. I used the same photo as above just added the new measurements.

http://reefcentral.com/gallery/data/500/200771PARCF.jpg

Then I did some out of water experiments on the old LED ( 50 LEDs) to prove the inverse square law . I made measurements at 12", 24" and 48"

12" 495 PAR
24" 145 PAR
48" 37 PAR

According to the calculations PAR should decrease at PAR2 = PAR1/(D2/D1)^2 as long as you are at least 5 times the distance of the size of the array. So my array is about 5" square so I should get accurate results at 25" away from the array. So I made a reading at 12" and 24" and calculated a result of 495/4 = 123.75 not quite the 145 that I measured thatâ€™s OK because I am not past the 25" mark. I made another reading at 48" and calculated PAR to be 145/4 = 36.25 much closer to my reading.

The point I'm trying to make here is the PAR reading will fall off dramatically not because it is penetrating water but just the fact of this inverse square law. I see lots of threads stated that water is the cause of the low PAR readings when it is just the physics of light at work. Water will only cause a small decrease in PAR compared with the inverse square loss. If you look at the first set of PAR readings my light is 6" above the tank and the tank is 18 " deep for a total of 24". The measured reading on the bottom of the tank is 147. This result is comparable to the reading I measured and calculated in air. Just a note these were very crude measurements and am sure there is some error tolerance.

JNye · 02/02/2009, 10:31 PM

I've actually read recently PAR travels through water better than air. Thanks for the work.

lynxvs · 02/03/2009, 07:13 AM

Really? do you remember where you read this?

jtma508 · 02/03/2009, 07:16 AM

Thanks for this lynx. It's good to see some science coming through all the speculation and urban legend.

evilc66 · 02/03/2009, 08:13 AM

I have tested this to be true with the work I have done.

What angle optics are you using for your array lynxvs?

lynxvs · 02/03/2009, 08:30 AM

I use a 36 degree wide angle lens part# FLP-W4-RE-HRF
from Fraen

evilc66 · 02/03/2009, 12:20 PM

Not bad. The middle number on the sandbed seems a little high from what I have experienced. I would have expected mid to high 200's with what you are running, but you aren't too far off if there was error.

lynxvs · 02/03/2009, 12:40 PM

You are right that middle reading was taken more to the left of what I show on the second pic.

JNye · 02/03/2009, 04:41 PM

Quote:

Really? do you remember where you read this?

I'm sorry I don't. I know it wasn't here though.

It could be easily tested for though. I can't right now the meter is lent out.

Freed · 02/03/2009, 04:46 PM

What are the specifics of the better output LED's? Lumen/??? watts/??? etc? Don't really know anything about LEDs but would like to be more in the know if I ever decide on X LED output vs. Y LED output. Thanks.

lynxvs · 02/03/2009, 06:50 PM

The Rebels I used in the first prototype were rated at 70 lumens at 350 mA and 130 Lumens at 700 mA. (Cool White) The Royal Blues were rated at 175 mW Radiometric power at 350 mA and 325 mW at 700 mA. I used these because they were available at the time and cheap and I knew I could upgrade easily. The new ones are rated at 100 Lumens at 350 mA and 180 at 700 mA. Royal Blues are rated at 275 mW at 350 mA and 525 mW at 700 mA. I increased the Cool white count from 12 to 18 and decreased Royal blue from 13 to 10. I also added two Cyan to help boost the light spectrum 500 nm range.

TandN · 02/03/2009, 07:35 PM

how many watts does it use total and how big of a tank is it good for ?

lynxvs · 02/03/2009, 09:58 PM

I measured about 6 amps at 24 V so thatâ€™s about 144 Watts. The light is 24" and has two arrays with 30 LEDs as I described above. I have it on a 29 gal (30"). but I wouldn't put it on a much longer tank without some dead spots. I designed the light so it can be expanded to any length easily. Here's some pictures that i'm sure everyone is sick of seeing.....

New Design

Old

lynxvs · 02/03/2009, 10:08 PM

I just realized I made an error in the first PAR reading above.The reading in the sandbed should have been 147 not 174 like I show. I guess that would make the statement below the picture make more sense....

Freed · 02/04/2009, 05:48 AM

So I'm looking for as many lumens per watt as possible per LED, right? What about nm ranges? At least 420nm for the (wavelength)? Any other params I'm looking for for the best LED output?

lynxvs · 02/04/2009, 07:16 AM

Yes, you should look for LEDs rated at least 100 Lumens. The spectral response your looking for is in the 400 - 700 nm range. The White LEDs are rated by color temp. look for the 6500 - 10000K range. I'm not an expert the spectral response of coral so if anybody else can put some input in here I would be grateful. Most LED lights that I have seen use a mixture of cool white, royal blue and cyan.

jtma508 · 02/04/2009, 10:05 AM

Gee lynx...

If the story in this thread...

http://www.reefbuilders.com/2009/02/...aquarium-leds/

...is true, you might be among the only game in town if people want to go LED. Time to start working on that USB/RS-232 interface.

cs12109 · 02/04/2009, 12:50 PM

Here's a link to Orbitec's LED products:

http://www.orbitec.com/bioproducts_led.html

The patent does seem to exclude manufacture of marine aquarium LED lighting products without permission/royalties to Orbitec. The problem is that the patent was granted in the first place.

lynxvs · 02/04/2009, 01:10 PM

Quote:

Originally posted by cs12109
Here's a link to Orbitec's LED products:

http://www.orbitec.com/bioproducts_led.html

The patent does seem to exclude manufacture of marine aquarium LED lighting products without permission/royalties to Orbitec. The problem is that the patent was granted in the first place.

This is an area I don't have a clue about.... Are you saying that any manufacture of aquarium LED lights has to pay royalties?
I assume nothing about this patent applies to a DIY project.

cs12109 · 02/04/2009, 01:19 PM

Quote:

Originally posted by lynxvs
This is an area I don't have a clue about.... Are you saying that any manufacture of aquarium LED lights has to pay royalties?
I assume nothing about this patent applies to a DIY project.

You can do DIY without a problem. The patent only affects those that stand to profit from patent infringement.

lynxvs · 02/04/2009, 01:26 PM

Quote:

Originally posted by jtma508
Gee lynx...

If the story in this thread...

http://www.reefbuilders.com/2009/02/...aquarium-leds/

...is true, you might be among the only game in town if people want to go LED. Time to start working on that USB/RS-232 interface.

Way to much pressure.......

02/02/2009, 09:51 PM	#1
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	LED PAR Readings I recently upgraded my DIY LED light with the following and took some PAR readings: A. Increased LED count to 60 vs 50. B. Added two cyan LEDs C. Upgraded LEDs to higher lumen bin. I am using an Apogee Quantum Sensor model SQ-110. I have three sets of readings that I took on my 29 Gal. The LED light is 6" off the surface. 50 LEDs Royal Blue and Cool white Rebels I measured the PAR on to of the eggcrate directly under one of the arrays and measured a PAR reading of 1450 60 LEDs Royal Blue, Cool White and Cyan with higher lumen bin I measured the PAR on to of the eggcrate directly under one of the arrays and measured a PAR reading of 2150 Then I broke out my old 65 Watt CF and made some measurements. I used the same photo as above just added the new measurements. http://reefcentral.com/gallery/data/500/200771PARCF.jpg Then I did some out of water experiments on the old LED ( 50 LEDs) to prove the inverse square law . I made measurements at 12", 24" and 48" 12" 495 PAR 24" 145 PAR 48" 37 PAR According to the calculations PAR should decrease at PAR2 = PAR1/(D2/D1)^2 as long as you are at least 5 times the distance of the size of the array. So my array is about 5" square so I should get accurate results at 25" away from the array. So I made a reading at 12" and 24" and calculated a result of 495/4 = 123.75 not quite the 145 that I measured thatâ€™s OK because I am not past the 25" mark. I made another reading at 48" and calculated PAR to be 145/4 = 36.25 much closer to my reading. The point I'm trying to make here is the PAR reading will fall off dramatically not because it is penetrating water but just the fact of this inverse square law. I see lots of threads stated that water is the cause of the low PAR readings when it is just the physics of light at work. Water will only cause a small decrease in PAR compared with the inverse square loss. If you look at the first set of PAR readings my light is 6" above the tank and the tank is 18 " deep for a total of 24". The measured reading on the bottom of the tank is 147. This result is comparable to the reading I measured and calculated in air. Just a note these were very crude measurements and am sure there is some error tolerance.

02/02/2009, 10:31 PM	#2
JNye Moved On Up Join Date: Feb 2007 Location: Lansing, IL Posts: 2,230	I've actually read recently PAR travels through water better than air. Thanks for the work. __________________ Joe Current Tank Info: it don't matter just don't bite it

02/03/2009, 04:46 PM	#10
Freed It's what it's Join Date: Mar 2003 Location: 41° 2' 45" N 85° 8' 43" W Posts: 7,579	What are the specifics of the better output LED's? Lumen/??? watts/??? etc? Don't really know anything about LEDs but would like to be more in the know if I ever decide on X LED output vs. Y LED output. Thanks. __________________ Freed Current Tank Info: 180gal(1120 watts of MH/VHO light), 60gal "sump", Deltec 601 calcium reactor, Euro Reef CS8-3+ skimmer, 20 gallon QT

02/04/2009, 05:48 AM	#15
Freed It's what it's Join Date: Mar 2003 Location: 41° 2' 45" N 85° 8' 43" W Posts: 7,579	So I'm looking for as many lumens per watt as possible per LED, right? What about nm ranges? At least 420nm for the (wavelength)? Any other params I'm looking for for the best LED output? __________________ Freed Current Tank Info: 180gal(1120 watts of MH/VHO light), 60gal "sump", Deltec 601 calcium reactor, Euro Reef CS8-3+ skimmer, 20 gallon QT

02/03/2009, 07:13 AM	#3
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	Really? do you remember where you read this?

02/03/2009, 07:16 AM	#4
jtma508 Premium Member Join Date: Jan 2008 Location: MA Posts: 1,232	Thanks for this lynx. It's good to see some science coming through all the speculation and urban legend.

02/03/2009, 08:13 AM	#5
evilc66 Registered Member. Join Date: Oct 2007 Posts: 245	I have tested this to be true with the work I have done. What angle optics are you using for your array lynxvs?

02/03/2009, 08:30 AM	#6
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	I use a 36 degree wide angle lens part# FLP-W4-RE-HRF from Fraen

02/03/2009, 12:20 PM	#7
evilc66 Registered Member. Join Date: Oct 2007 Posts: 245	Not bad. The middle number on the sandbed seems a little high from what I have experienced. I would have expected mid to high 200's with what you are running, but you aren't too far off if there was error.

02/03/2009, 12:40 PM	#8
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	You are right that middle reading was taken more to the left of what I show on the second pic.

02/03/2009, 06:50 PM	#11
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	The Rebels I used in the first prototype were rated at 70 lumens at 350 mA and 130 Lumens at 700 mA. (Cool White) The Royal Blues were rated at 175 mW Radiometric power at 350 mA and 325 mW at 700 mA. I used these because they were available at the time and cheap and I knew I could upgrade easily. The new ones are rated at 100 Lumens at 350 mA and 180 at 700 mA. Royal Blues are rated at 275 mW at 350 mA and 525 mW at 700 mA. I increased the Cool white count from 12 to 18 and decreased Royal blue from 13 to 10. I also added two Cyan to help boost the light spectrum 500 nm range.

02/03/2009, 07:35 PM	#12
TandN Registered Member. Join Date: Aug 2006 Location: NYC Posts: 2,009	how many watts does it use total and how big of a tank is it good for ?

02/03/2009, 09:58 PM	#13
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	I measured about 6 amps at 24 V so thatâ€™s about 144 Watts. The light is 24" and has two arrays with 30 LEDs as I described above. I have it on a 29 gal (30"). but I wouldn't put it on a much longer tank without some dead spots. I designed the light so it can be expanded to any length easily. Here's some pictures that i'm sure everyone is sick of seeing..... New Design Old

02/03/2009, 10:08 PM	#14
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	I just realized I made an error in the first PAR reading above.The reading in the sandbed should have been 147 not 174 like I show. I guess that would make the statement below the picture make more sense....

02/04/2009, 07:16 AM	#16
lynxvs Registered Member Join Date: Sep 2008 Location: MA Posts: 189	Yes, you should look for LEDs rated at least 100 Lumens. The spectral response your looking for is in the 400 - 700 nm range. The White LEDs are rated by color temp. look for the 6500 - 10000K range. I'm not an expert the spectral response of coral so if anybody else can put some input in here I would be grateful. Most LED lights that I have seen use a mixture of cool white, royal blue and cyan.

02/04/2009, 10:05 AM	#17
jtma508 Premium Member Join Date: Jan 2008 Location: MA Posts: 1,232	Gee lynx... If the story in this thread... http://www.reefbuilders.com/2009/02/...aquarium-leds/ ...is true, you might be among the only game in town if people want to go LED. Time to start working on that USB/RS-232 interface.

02/04/2009, 12:50 PM	#18
cs12109 Registered Member Join Date: Dec 2008 Posts: 74	Here's a link to Orbitec's LED products: http://www.orbitec.com/bioproducts_led.html The patent does seem to exclude manufacture of marine aquarium LED lighting products without permission/royalties to Orbitec. The problem is that the patent was granted in the first place.