(Disclosure, dropped the phone and broke the screen today crossing a street, so turns out reef tank was not the biggest risk for the phone after all). PAR was measured using an Apogee MQ-200 with the photosensor set at the surface of the water (the bottom of the probe was below water). The values provided below are the peak/max value I could reproduce 3 times.
This took me a while to get back to. I used the lux meter on my phone and the PAR meter borrowed from the reef club and I have some measurements to share with the group here. I disclose up front that lighting is not my expertise, but then that has never stopped me from anything before.
Lux was measured from my iPhone (5) by floating the phone on the surface of the water using a clear ziplock storage container lid. Only went in the water twice and still works
Tank is a Marinland 110 gallon (48" x 18" x 30")
HO bulbs run on a BRS HO dimmable ATI ballast set at 100% via Apex.
The bulbs are located 14" apart, so I cannot get a surface reading of both bulbs combined, however the reading are not exclusive either. I can't run one at a time so I can't say how much is bleed over.
- HO 54W Geisemann Actinic, Lux: 31,023, PAR: 215
- HO 54W Geisemann Aquablue Azure, Lux: 31,023, PAR: 175
LED lighting is provided by four AquaIllumination Hydra26's (non-HD models). The lights are oriented with the pucks perpendicular to the tank at 10" spacing such that each side of the tank has 4 pucks in a quad pattern. Each color channel was run at 100% and then all combined at 100%.
Unfortunately, I shattered the glass on my phone today so I did not get a good Lux reading on the All LED's, however in my mind this should be additive...so 99,369. A few notes, first all the PARs measured total up to 1545, and 1550 was actually measured, so I have good feeling on my PAR measurements. Secondly, I did not over look that green has more lux than deep blue, despite having only 2 LEDs per fixture vs 8. I suspect I have a bum PAR reading on one of those two, but Im not sure which one. With the glass cracked (right over the camera), I can't get another reading.
- Red, Lux: 1,071, PAR: 70
- Green, Lux: 5,427, PAR: 75
- Deep Blue, Lux: 5,247, PAR: 290
- Royal Blue, Lux: 12,069, PAR: 500
- Indigo/Violet, Lux: 2,565, PAR: 70
- UltraViolet, Lux: 423, PAR: 40
- Cool White, Lux: 72,567, PAR: 500
- All LEDs, Lux: ?, PAR: 1,550
Now, to put these numbers into perspective, I measured PAR at 43 (coral mounting) points throughout my tank for each color channel and for all lights. The HO lighting at 100% has an average PAR of 48. The LEDs at all 100% has an average PAR of 272.
The settings I use on my lights currently produces a total blended light with an average PAR of 200. The PAR range at the coral mounts ranges from 40 to 320. The corresponding PAR at the surface was 500 and the Lux was 57,080.
My tank is primarily LPS so I find the number satisfying. I do have a few corals with heavy bleaching and I now see why. These will be relocated to more shaded areas. I will soon be looking for an easy SPS to put into my sets that are PAR 240 or higher.
I did calculate the Lux to PAR and PAR to Lux factors and these did NOT correspond to the tabulated values in the Apogee manual. I leave this information for you all to parse.
but I am considering other factors, tank temperature being another.
I have to say. Use a lux meter. Not a phone.This took me a while to get back to. I used the lux meter on my phone and the PAR meter borrowed from the reef club and I have some measurements to share with the group here. I disclose up front that lighting is not my expertise, but then that has never stopped me from anything before.
Lux was measured from my iPhone (5) by floating the phone on the surface of the water using a clear ziplock storage container lid. Only went in the water twice and still works
Tank is a Marinland 110 gallon (48" x 18" x 30")
HO bulbs run on a BRS HO dimmable ATI ballast set at 100% via Apex.
The bulbs are located 14" apart, so I cannot get a surface reading of both bulbs combined, however the reading are not exclusive either. I can't run one at a time so I can't say how much is bleed over.
- HO 54W Geisemann Actinic, Lux: 31,023, PAR: 215
- HO 54W Geisemann Aquablue Azure, Lux: 31,023, PAR: 175
LED lighting is provided by four AquaIllumination Hydra26's (non-HD models). The lights are oriented with the pucks perpendicular to the tank at 10" spacing such that each side of the tank has 4 pucks in a quad pattern. Each color channel was run at 100% and then all combined at 100%.
Unfortunately, I shattered the glass on my phone today so I did not get a good Lux reading on the All LED's, however in my mind this should be additive...so 99,369. A few notes, first all the PARs measured total up to 1545, and 1550 was actually measured, so I have good feeling on my PAR measurements. Secondly, I did not over look that green has more lux than deep blue, despite having only 2 LEDs per fixture vs 8. I suspect I have a bum PAR reading on one of those two, but Im not sure which one. With the glass cracked (right over the camera), I can't get another reading.
- Red, Lux: 1,071, PAR: 70
- Green, Lux: 5,427, PAR: 75
- Deep Blue, Lux: 5,247, PAR: 290
- Royal Blue, Lux: 12,069, PAR: 500
- Indigo/Violet, Lux: 2,565, PAR: 70
- UltraViolet, Lux: 423, PAR: 40
- Cool White, Lux: 72,567, PAR: 500
- All LEDs, Lux: ?, PAR: 1,550
Now, to put these numbers into perspective, I measured PAR at 43 (coral mounting) points throughout my tank for each color channel and for all lights. The HO lighting at 100% has an average PAR of 48. The LEDs at all 100% has an average PAR of 272.
The settings I use on my lights currently produces a total blended light with an average PAR of 200. The PAR range at the coral mounts ranges from 40 to 320. The corresponding PAR at the surface was 500 and the Lux was 57,080.
My tank is primarily LPS so I find the number satisfying. I do have a few corals with heavy bleaching and I now see why. These will be relocated to more shaded areas. I will soon be looking for an easy SPS to put into my sets that are PAR 240 or higher.
I did calculate the Lux to PAR and PAR to Lux factors and these did NOT correspond to the tabulated values in the Apogee manual. I leave this information for you all to parse.
If your taking a reading at the top of the tank you can pretty much estimate the rest or the tank.
No you won't lose that much. It's difficult to guage beacuse there Ian a slight loss from refraction but the bigger difference is actually in the optics of the fixture.
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Losses from water happen roughly logrithmic.....or levels drop by about 4 for every doubling of the depth I still can't find a good resource that explains this in laymens terms...it's something I heard a long time ago during my freshwater planted tank days. @Dana Riddle is this roughly correct as stated and can/would you explain it better by chance?
That's a very rough way of looking at it so it's easier to think about....but lots of things impact this number....from the lenses on your LED's to what you feed, whether you use carbon, etc.
Losses in air are roughly linear. Dropping by half for every doubling of distance from the light source. Lenses and things also affect this, but generally less in magnitude and fewer in number than water-related factors.
Thankyou Saltyfilmfolks !! This explains a lot to me .. now I can finally use my lux meterI use a photographer's meter, it does footcandles and lux. Around the tank I use a $14 luxmeter from amazon. Look for one that is 100,000 or 200,000 lux maximum.
Milwaukee makes a submersible one for $75. The Seneye lux meter is not a cosine corrected light meter and the readings are quite different and noted lux/par conversion dont work with it.
Its not an imperative to know the lux of the tank its just an optional way to check you par settings if a par meter is not available. but I do recommend it to par meter users who are really interested in understanding light.
In short, lux is intensity, intensity + spectrum is PAR.
A basic lux/par conversion constant for led at a 1;1 ratio is 60. Ie 6000 lux = 100 par. as the color changes to a more blue spectrum the constant is higher 65-75.
A typical MH say 20k radium bulb is around 50 as a constant. (some much lower) so 6000 is 120 par
Most t5 fall much lower in the 40 range. 6000 lux=150 par
When doing lux par conversion on leds with wacky color setting from the internet rumor mill, I run the conversion at 60, 65, 70 and 75 to estimate the range I'm likely working in.
20,000lux/60=333 par 20,oo0lux/70=285 par etc.......................Btw, 20,000 lux / 50 =400.,,,,,,,,,,this is worthy of note, MH and T5 in general have more par with less intensity. most believe it is the opposite.
Another use of the lux meter is to have a store or manufactures turn it up to full power and test a 12in. you immediately see the the difference in intensity between models (ap700 a 80 for instance) and then know approx what it can deliver when selecting them for your tank.
You can also take it to the lfs like i do to see how much light they use over the frag tank. I can do it so fast they don't notice, but round here, they all know me so they don't mind.(and then use more light on their SPS tanks.
@mcarroll I find it particularly interesting in the last 18 months, the large number of users and random questions pertaining to lux and par and the large number of users who now own lux meters and do the conversions.
After 3 years of flaming and debate, it appears, Two nerds can change the world.
No sweat!Thankyou Saltyfilmfolks !! This explains a lot to me .. now I can finally use my lux meter
Took me a while to find light data I gathered while diving off Kailua-Kona coast. Probably raises more questions than it answers...
I think it answers a lot myself.Took me a while to find light data I gathered while diving off Kailua-Kona coast. Probably raises more questions than it answers...
