Lux meters to check Led????

john.m.cole3 · Jul 11, 2017

I have had the LUX meter convo with all of my local reefers and I get this certain look, followed by disbelief that such a device could be so useful. In Mr. Riddle's MACNA talk 2016, he goes over how our vorals do not need as much light as we might think they do. With that being said, I find a LUX meter very easy to use to measure your light when ramping them up like you do when acclimating corals. A LUX meter is also useful for when you upgrade tanks and transition your lighting over. It's fun to talk about and I like the simplicity of use. Thanks salty and Matt for shining the light on this sunject.

mcarroll · Jul 12, 2017

dacianb said:
I am optical engineer as profession and in this area we use only one way to measure the light - radiometric power.

saltyfilmfolks said:
For the laymen or hobbiest . Lux and par and more than enough.

It's easy to focus too much on "what's cheapest" or "what's best" sometimes and sort of forget to just consider "what it takes" to get the job at hand done.

We're not submitting articles to science journals or generating data for statistical analysis...or anything else like that. We're make relative adjustments to reef lights and we just need a way to calibrate those changes.

saltyfilmfolks · Jul 12, 2017

mcarroll said:
It's easy to focus too much on "what's cheapest" or "what's best" sometimes and sort of forget to just consider "what it takes" to get the job at hand done.

We're not submitting articles to science journals or generating data for statistical analysis...or anything else like that. We're make relative adjustments to reef lights and we just need a way to calibrate those changes.

He and I have had this conversation before.

Quite a good thread actually.
https://www.reef2reef.com/threads/confuse-about-intensity-and-spectrum.231543/page-2#post-2709640

Michael Montgomery · Jul 12, 2017

@saltyfilmfolks ....
OKAY... SO... What would you suggest for the "lighting AND reef newbie" to do with their new LUX meter? What would be the best process for evaluating a new light purchase? What 'numbers' should we be trying to target?

I know... it's a LOT to ask for..... aaaand the 'answers' arent so easy.

saltyfilmfolks · Jul 12, 2017

Michael Montgomery said:
@saltyfilmfolks ....
OKAY... SO... What would you suggest for the "lighting AND reef newbie" to do with their new LUX meter? What would be the best process for evaluating a new light purchase? What 'numbers' should we be trying to target?

I know... it's a LOT to ask for..... aaaand the 'answers' arent so easy.

Hahahaha. Well......
For a total newb, your likey up a creek. ;Wideyed

For a newer newb, look at the tanks that you like and the par that those tanks run in By asking questions and looking a tank par charts and note what are high med and low light coral.
Look at manufacturer Par specs and the distance from the light they are taken at. Those specs are given at full power and 1:1 color ratios. Choose a light that meets or exceeds the par specs you want or need. Manufactures like AI and Radion offer several different models with with different power levels.

(I think its worthy to note here, that along with Dana R's work, this is how I confirmed the the number 60. I compared several of my lights lux readings to the published par charts they lined up almost exactly)

Even though I am metering in lux, I am at all times thinking in par.
I've spoken to folks who actually do the opposite. Mainly because it's easy and its simply a quantified number to follow. IE 22,000 lux doesn't seem enough, bump it to 26,000 lux, and see how it goes.

Run the numbers. Take an arbitrary luc number and divide it by 60(my prefered) but also 65, 70 and 75 and also 50 and 55 and note the very slight change in par.
Do that again with the lux number of 6000. I consider that one important. 6000 lux at 60 is 100 par.

So when you get your tank, set the lux at the top of the water on a best guess for par you want, then drop it 50 to 100 par to acclimate. Now you have a solid number to slowly increase or decrease the intensity. 6000 lux or 100 par, or 3000 lux or 50 par.
And yes, guesstimating the amount of blue and other color factors that change the conversion constant of 60. More than likely, its closer to 70 than 60. We love too much blue.
Some may say this is not precise, but if you speak to Par meter users its very much the same process as they search for the "sweet spot".

Once you set an intensity, minor color changes are IMO, just that. Minor, and likely effect both par and lux minimally.

Additionally, if someone has their tank set up just like yours, you can copy all of their colors, and match the lux. And subsequent par.

You can also go to the lfs, and see how much light is over their tanks when you buy a frag. keep in mind most don't propagate coral , just store it till you buy it.

I also do recommend, (as a Gaffer, Photographer, and reefer) Wander around the house with the meter. Go out side. It helps to understand how very little, or hoe very much light is around us. This IMO, will hlep later as you set the ramp time and levels to not exceed a maximum DLI. The amount of light I have in the am and the very last of the PM is less than you have in the bathroom. But I can see the tank quite clearly at 75 lux. My keyboard right this second is 46 lux and the windows are all open.

Michael Montgomery · Jul 12, 2017

saltyfilmfolks said:
Hahahaha. Well......
For a total newb, your likey up a creek. ;Wideyed

For a newer newb, look at the tanks that you like and the par that those tanks run in By asking questions and looking a tank par charts and note what are high med and low light coral.
Look at manufacturer Par specs and the distance from the light they are taken at. Those specs are given at full power and 1:1 color ratios. Choose a light that meets or exceeds the par specs you want or need. Manufactures like AI and Radion offer several different models with with different power levels.

(I think its worthy to note here, that along with Dana R's work, this is how I confirmed the the number 60. I compared several of my lights lux readings to the published par charts they lined up almost exactly)

Even though I am metering in lux, I am at all times thinking in par.
I've spoken to folks who actually do the opposite. Mainly because it's easy and its simply a quantified number to follow. IE 22,000 lux doesn't seem enough, bump it to 26,000 lux, and see how it goes.

Run the numbers. Take an arbitrary luc number and divide it by 60(my prefered) but also 65, 70 and 75 and also 50 and 55 and note the very slight change in par.
Do that again with the lux number of 6000. I consider that one important. 6000 lux at 60 is 100 par.

So when you get your tank, set the lux at the top of the water on a best guess for par you want, then drop it 50 to 100 par to acclimate. Now you have a solid number to slowly increase or decrease the intensity. 6000 lux or 100 par, or 3000 lux or 50 par.
And yes, guesstimating the amount of blue and other color factors that change the conversion constant of 60. More than likely, its closer to 70 than 60. We love too much blue.
Some may say this is not precise, but if you speak to Par meter users its very much the same process as they search for the "sweet spot".

Once you set an intensity, minor color changes are IMO, just that. Minor, and likely effect both par and lux minimally.

Additionally, if someone has their tank set up just like yours, you can copy all of their colors, and match the lux. And subsequent par.

You can also go to the lfs, and see how much light is over their tanks when you buy a frag. keep in mind most don't propagate coral , just store it till you buy it.

I also do recommend, (as a Gaffer, Photographer, and reefer) Wander around the house with the meter. Go out side. It helps to understand how very little, or hoe very much light is around us. This IMO, will hlep later as you set the ramp time and levels to not exceed a maximum DLI. The amount of light I have in the am and the very last of the PM is less than you have in the bathroom. But I can see the tank quite clearly at 75 lux. My keyboard right this second is 46 lux and the windows are all open.

A most excellent post... Thank you so much.

Monkeynaut · Jul 12, 2017

You may find these links helpful. I did.

http://www.bulkreefsupply.com/video/view/brstv-investigates-what-par-meter-is-the-best/

ROUND 2! PAR Shootout! Seneye Reef Monitor v2 VS. Apex PMK vs. Apogee MQ-510 Full

https://www.reef2reef.com/index.php...2-VS.-Apex-PMK-vs.-Apogee-MQ-510-Full.292681/

clsanchez77 · Jul 13, 2017

Ok, so this post has me trying to fire up the old noodle again. My entire career in this hobby has always been about PAR, going back to the old 650K Iwasaki vs 10,000K Ushio debate...and of course with Actinic VHO's! So, I downloaded the "Lightmeter" Lux App on my phone and took some measurements. I put my lighting on the peak mid-day settings and my peak lux was 850 at the surface of the water.

Our club's PAR meter just arrived so I will start collecting some samples at the surface for Lux comparison as well as at my coral mounting points.

I am curious as to your initial impression of 850...not knowing anything else about the tank.

Also, I have not been able to locate any observed lux readings on a coral reef. I have found countless sources of Lux at the surface for various points of the day. I have to admit I did not think 100,000 lux is reasonable for a reef tank, but I'm not the expert

. However, the corals we keep come from anywhere between 1 meter of water depth to 20 meters of water depth or more. So the actual lux readings on the reef will be dampened significantly by water attenuation. In our tanks, water attenuation is insignificant (0.2 meters on average) relative to the spread of a point source at square of the distance. I'm not sure how these two losses compare. I guess my point is what Lux would be needed at the surface of a reef tank so the corals are getting a similar lux as they would on a reef when accounting for water adsorption of the light.

FWIW, the tank is 30" deep, the rock work is arranged to be a flat structure at the mid point with mostly LPS and gorgonias. My high points will have "low light" SPS and the areas below the LPS will be polyps and eventually leptoseris. The remainder of the tank will be coralline and sponge.

saltyfilmfolks · Jul 13, 2017

clsanchez77 said:
Ok, so this post has me trying to fire up the old noodle again. My entire career in this hobby has always been about PAR, going back to the old 650K Iwasaki vs 10,000K Ushio debate...and of course with Actinic VHO's! So, I downloaded the "Lightmeter" Lux App on my phone and took some measurements. I put my lighting on the peak mid-day settings and my peak lux was 850 at the surface of the water.

Our club's PAR meter just arrived so I will start collecting some samples at the surface for Lux comparison as well as at my coral mounting points.

I am curious as to your initial impression of 850...not knowing anything else about the tank.

Also, I have not been able to locate any observed lux readings on a coral reef. I have found countless sources of Lux at the surface for various points of the day. I have to admit I did not think 100,000 lux is reasonable for a reef tank, but I'm not the expert . However, the corals we keep come from anywhere between 1 meter of water depth to 20 meters of water depth or more. So the actual lux readings on the reef will be dampened significantly by water attenuation. In our tanks, water attenuation is insignificant (0.2 meters on average) relative to the spread of a point source at square of the distance. I'm not sure how these two losses compare. I guess my point is what Lux would be needed at the surface of a reef tank so the corals are getting a similar lux as they would on a reef when accounting for water adsorption of the light.

FWIW, the tank is 30" deep, the rock work is arranged to be a flat structure at the mid point with mostly LPS and gorgonias. My high points will have "low light" SPS and the areas below the LPS will be polyps and eventually leptoseris. The remainder of the tank will be coralline and sponge.

850 at peak would indicate and error. My tanks are at about 350,000 at the top.

Lux and par are both effected by Depth of water. Both are light and measurements of It.
Think in par and those needs and use lux to estimate it.

litenyaup · Jul 13, 2017

smilereef2017 said:
Seneye reef monitor works fine for this application

Only if you don't use apple products. It will not work on a mac and will only work if you buy the sws module on iPhone.

Monkeynaut · Jul 13, 2017

litenyaup said:
Only if you don't use apple products. It will not work on a mac and will only work if you buy the sws module on iPhone.

I did buy the SWS and WIFI module.
To clear up what you said. It does work for me using my mac laptop. It will work from any computer so long as it has a web browser.

revhtree · Jul 13, 2017

Nice thread!

mcarroll · Jul 13, 2017

clsanchez77 said:
I put my lighting on the peak mid-day settings and my peak lux was 850 at the surface of the water.

Agree with Salty, that's an error....either the app was using the down-facing camera that's away from the lights, or the app simply isn't calibrated for your smartphone's light sensor.

There's usually a switch or button in the app to switch cameras, so try that first.

clsanchez77 · Jul 13, 2017

mcarroll said:
Agree with Salty, that's an error....either the app was using the down-facing camera that's away from the lights, or the app simply isn't calibrated for your smartphone's light sensor.

There's usually a switch or button in the app to switch cameras, so try that first.

Thanks folks, I will try again tonight and see what I find. Worst comes to worst, Ill just pickup an actual sensor.

clsanchez77 · Jul 13, 2017

mcarroll said:
Agree with Salty, that's an error....either the app was using the down-facing camera that's away from the lights, or the app simply isn't calibrated for your smartphone's light sensor.

There's usually a switch or button in the app to switch cameras, so try that first.

Let me re-phrase the question..."So, is a lux of 850 on the top of the water from the light bouncing off the bottom good?"

saltyfilmfolks · Jul 13, 2017

clsanchez77 said:
Let me re-phrase the question..."So, is a lux of 850 on the top of the water from the light bouncing off the bottom good?"

Lol. It's an irrelevant reading.

litenyaup · Jul 13, 2017

Monkeynaut said:
I did buy the SWS and WIFI module.
To clear up what you said. It does work for me using my mac laptop. It will work from any computer so long as it has a web browser.

I could not get it to download any program to make it work. Either way she gone. Got a mq200 now and it works extremely well.

clsanchez77 · Jul 13, 2017

saltyfilmfolks said:
850 at peak would indicate and error. My tanks are at about 350,000 at the top.

Lux and par are both effected by Depth of water. Both are light and measurements of It.
Think in par and those needs and use lux to estimate it.

Are you taking that measurement at the top of the water or just under the light fixture? If I put the phone right at the water, close enough to get my fingers wet, I am reading 21,000 lux. If I put the phone right at one white LED, I get 75,000. So Im not approaching your numbers.

saltyfilmfolks · Jul 13, 2017

clsanchez77 said:
Are you taking that measurement at the top of the water or just under the light fixture? If I put the phone right at the water, close enough to get my fingers wet, I am reading 21,000 lux. If I put the phone right at one white LED, I get 75,000. So Im not approaching your numbers.

Astou move the meter across the top of the water , you'll find the hot spot and fall off spots of the light.
Fwiw, that's why I prefer large multi emitters that cover the tank rather than puck style emitters.

21,000 sounds correct.