Reef Central Online Community
Tampa Bay Saltwater

Home Forum Here you can view your subscribed threads, work with private messages and edit your profile and preferences View New Posts View Today's Posts

Find other members Frequently Asked Questions Search Reefkeeping ...an online magazine for marine aquarists Support our sponsors and mention Reef Central

Go Back   Reef Central Online Community > General Interest Forums > Lighting, Filtration & Other Equipment
Register Blogs FAQ Calendar Mark Forums Read

Notices

User Tag List

Reply
Thread Tools
Old 02/02/2009, 08:51 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 that’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.


lynxvs is offline   Reply With Quote
Old 02/02/2009, 09:31 PM   #2
JNye
Moved On Up
 
JNye's Avatar
 
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
JNye is offline   Reply With Quote
Old 02/03/2009, 06:13 AM   #3
lynxvs
Registered Member
 
Join Date: Sep 2008
Location: MA
Posts: 189
Really? do you remember where you read this?


lynxvs is offline   Reply With Quote
Old 02/03/2009, 06:16 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.


jtma508 is offline   Reply With Quote
Old 02/03/2009, 07:13 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?


evilc66 is offline   Reply With Quote
Old 02/03/2009, 07:30 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


lynxvs is offline   Reply With Quote
Old 02/03/2009, 11:20 AM   #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.


evilc66 is offline   Reply With Quote
Old 02/03/2009, 11:40 AM   #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.


lynxvs is offline   Reply With Quote
Old 02/03/2009, 03:41 PM   #9
JNye
Moved On Up
 
JNye's Avatar
 
Join Date: Feb 2007
Location: Lansing, IL
Posts: 2,230
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.


__________________
Joe

Current Tank Info: it don't matter just don't bite it
JNye is offline   Reply With Quote
Old 02/03/2009, 03:46 PM   #10
Freed
It's what it's
 
Freed's Avatar
 
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
Freed is offline   Reply With Quote
Old 02/03/2009, 05:50 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.


lynxvs is offline   Reply With Quote
Old 02/03/2009, 06:35 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 ?


TandN is offline   Reply With Quote
Old 02/03/2009, 08:58 PM   #13
lynxvs
Registered Member
 
Join Date: Sep 2008
Location: MA
Posts: 189
I measured about 6 amps at 24 V so that’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 is offline   Reply With Quote
Old 02/03/2009, 09:08 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....


lynxvs is offline   Reply With Quote
Old 02/04/2009, 04:48 AM   #15
Freed
It's what it's
 
Freed's Avatar
 
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
Freed is offline   Reply With Quote
Old 02/04/2009, 06:16 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.


lynxvs is offline   Reply With Quote
Old 02/04/2009, 09:05 AM   #17
jtma508
Premium Member
 
Join Date: Jan 2008
Location: MA
Posts: 1,232
Gee lynx...

If the story in this thread...

http://www.************.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.


jtma508 is offline   Reply With Quote
Old 02/04/2009, 11:50 AM   #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.


cs12109 is offline   Reply With Quote
Old 02/04/2009, 12:10 PM   #19
lynxvs
Registered Member
 
Join Date: Sep 2008
Location: MA
Posts: 189
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.


lynxvs is offline   Reply With Quote
Old 02/04/2009, 12:19 PM   #20
cs12109
Registered Member
 
Join Date: Dec 2008
Posts: 74
DIY

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.


cs12109 is offline   Reply With Quote
Old 02/04/2009, 12:26 PM   #21
lynxvs
Registered Member
 
Join Date: Sep 2008
Location: MA
Posts: 189
Quote:
Originally posted by jtma508
Gee lynx...

If the story in this thread...

http://www.************.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.......


lynxvs is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -6. The time now is 05:06 PM.


TapaTalk Enabled

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Use of this web site is subject to the terms and conditions described in the user agreement.
Reef CentralTM Reef Central, LLC. Copyright ©1999-2014
User Alert System provided by Advanced User Tagging v3.3.0 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.