Why all the talk about LUX?

[saltyfilmfolks]

I've understood as you do and wonder myself about it and these free apps people using to place corals?

I don't advise the use of the apps. A camera uses reflected light. A par and lux or footcandle meter measures incedent light.
Plus cameras have color issues like limiters and balanceers used to make a nice picture.
And it's a lot harder to use.

I use my meter to establish a range in my tank. If it were a par meter I would do the same. Super high at the top and super low at the bottom because it's deep. So now I have a bit better idea of what goes where.

That said my first really sucessful acro is at the same distance from the light that my colony of Xenia are at the very top of the tank.
I have have three ai sol at at 65% eight inches from the corals. No matter how you measure it. That's a lot of light.

 

[gus6464]

Agreed. I think that's also where PUR comes in too.

I'll go back to a per meter was not made for us. You can have great par in your orchid garden. Not goona work that great for a deep water coral.
You have to look at the spectrum amounts provided by the fixture as well. Not just amounts on the par meter as they too can be deceiving

That's why my claim is if you have a good marine coral fixture with good spectrum you can then just measure its intensity and get pretty darned close.
If it were plants I'd say the same but it would be a different fixture w different spectrum. Yellow and red give you great par.

So yea you need to understand all three. What kind of PAR does your coral want in what intensity


Hey thanks for a great thread and debate. I hope to learn a lot.

PAR is PAR. Meaning the measured flat quantum response between 400-700nm. 400 PAR in open air and 400 PAR underwater with a white light is still 400 PAR. A lux meter does absolutely nothing to measure PUR and requires a ton of different conversion factors when measuring an led luminaire with many different short bandwidth diodes to get an accurate PAR reading.

 

[saltyfilmfolks]

Have

Have you ever seen a 400nm LED? To the eye it puts out almost no visible light. A lux meter will read almost 0. If I need to have a par meter next to your lux meter so you can do the lux conversion factor why do you need the lux meter in the first place?

You can't just say "ohh you need to have a lux reading in the whatever range" without knowing the wavelength and source of light being measured. A light with all 400-500nm leds and a tiny hint of lime or mint will look whiter to a person and still read super low lux when the PAR will be sky high.

you put a lux meter and a par meter next to a 400 mm led? Curious.

And yes I agree. You need to know the spectrum on the light. ESP if you want to dig deep. And again if your growing coral or orchids.

And I don't agree it's sky high. There will be or should be a matmatical correlation.

Look again at the apogee site. Yea some fixture are sky high in par. Kind of mind boggling really. But they still present numbers for it.

 

[madweazl]

Have you ever seen a 400nm LED? To the eye it puts out almost no visible light. A lux meter will read almost 0. If I need to have a par meter next to your lux meter so you can do the lux conversion factor why do you need the lux meter in the first place?

You can't just say "ohh you need to have a lux reading in the whatever range" without knowing the wavelength and source of light being measured. A light with all 400-500nm leds and a tiny hint of lime or mint will look whiter to a person and still read super low lux when the PAR will be sky high.

His point is that if you measure the LUX and the PAR of that light, you have a number that can be useful to other members down the road.

 

[gus6464]

Have

you put a lux meter and a par meter next to a 400 mm led? Curious.

And yes I agree. You need to know the spectrum on the light. ESP if you want to dig deep. And again if your growing coral or orchids.

And I don't agree it's sky high. There will be or should be a matmatical correlation.

Look again at the apogee site. Yea some fixture are sky high in par. Kind of mind boggling really. But they still present numbers for it.

A 450nm diode can easily be measured with a lux meter and then a par meter to come up with a conversion factor. The second I throw the lime LED into the mix the conversion factor becomes useless because that small amount of lime is going to measure considerably more on the lux meter and throw the whole thing out of whack.

A lux meter measures ~3% of actual output in the 450nm only range and 100% at 550nm. You put a light source with those two wavelengths together and you margin of error is massive towards the blue which is what we actually need.

 

[saltyfilmfolks]

still say that an article explaining the differences and some detailed explanation of how LUX should be understood in relation to PAR (and both of these in relation to corals and other photosynthetic marine life) would be useful. It would need to sufficiently explain what LUX readings can do and what they can't (same for PAR). Ultimately, it would give a fair and balanced way of looking at this conversation...at least that's what I'd like to read.

Totally agreed. And well said
Unfortunately I hav not found the simple easy to read light article for intermediates. It's buried in a hundred other articles and as we see here subject to interpretation.

I and macarroll probably the biggest loudmouths proponents of lux here do not ever say it's a replace ment it but it gets you close and is the first step in understanding the relationship of spectrum and intensity.

Close in intensity of a fixture with known good spectrum is actuall good enough. It is.
Because corals have a broad range of par they will live in.

Yes you do have to be careful of the quality of meter you choose. That goes for par too. I have the red meter from Amazon and a spectra 4a that costs $500. They are very close appearantly. Milwaukee makes one for $75 I think. No one seems to say the $250 garden par meter is any good but in theory it should be right? It's a par meter. No one will reccomend it because it's not part of the fashionable trend.

Bashing the use of a meter because of theoretical error in readings is not helpful.
That happens with chem test kits too and there's no flame war. Well maybe on face book. I don't know.

Lux is a good enough learning tool. I've never claimed more than that. Explaining the relationship between The two would be very handy. Explaining the limits of each of them would be intensely helpful for a lot of people. Understanding what coras need is actually a much larger subject that deserves much more time than debating the proven means to test it. Finding the limits of both meters and helping others learn what those limits are would be better for a boon to the community in general and publishing lux par conversions as estimates would help a lot of folks out.

Were I to be able to afford a par meter that's what I would do with my lux meter.

 

[dragon99]

@gus6464 Slightly off-topic, do you have pics or something of a blue/lime light. That sounds awesome.

 

[saltyfilmfolks]

Lol

 

[gus6464]

@gus6464 Slightly off-topic, do you have pics or something of a blue/lime light. That sounds awesome.

Actually I do let me dig it up. Dave from nanobox was showing off a prototype puck with mint LEDs and showed a picture with white channel at 10% and blue and mint at 70% or so. Mint and lime are basically the same with mint having a spectral graph skewing more on the blue while lime skews more yellow.

 

[john.m.cole3]

Here is why and how I use LUX.

why: It cost $15 for a meter. If I waited o save up for a PAR meter, I might still be waiting.

How: say you want to raise or lower your _____ fixture for whatever reason. A LUX reading can help you dial in the same intensity your fixture gave off at its previous height. Also, I have a LPS or softie coral and want to know where lower light intensities will be in my tank. A LUX meter will show how far away from the center of the fixture I need to go. Also when I ramp up my fixture, I know to go in less than 2,000 LUX increments.

It's not a PAR meter, but it is helpful.

 

[saltyfilmfolks]

A 450nm diode can easily be measured with a lux meter and then a par meter to come up with a conversion factor. The second I throw the lime LED into the mix the conversion factor becomes useless because that small amount of lime is going to measure considerably more on the lux meter and throw the whole thing out of whack.

A lux meter measures ~3% of actual output in the 450nm only range and 100% at 550nm. You put a light source with those two wavelengths together and you margin of error is massive towards the blue which is what we actually need.

It becomes a different conversion factor as now it's a different fixture. No?

Lux went up. Par didnt budge. Higher conversion number.

That should be similar to the prob of increasing the par in a multi channel led.
What color do you chose to increase the par.
The par goes up as does the lux but do you really want to add yellow.

That's up to the users understanding of what a coral needs. .
Both are actually flawed systems and useless unless you understand what the coral needs not just how much you get on a meter.

Not to take away from the metering teqnique debate. But it's even more interesting that no matter how you measure it. Science is now saying that 350 par is enough. Many users ESP mh are routinely giving in exess of 1500 par and get amazing results. I think that's a much more interesting thing to think about than giving advice to a newb so he stops frying his coral by using a lux meter and begin to understand par.

 

[gus6464]

It becomes a different conversion factor as now it's a different fixture. No?

Lux went up. Par didnt budge. Higher conversion number.

That should be similar to the prob of increasing the par in a multi channel led.
What color do you chose to increase the par.
The par goes up as does the lux but do you really want to add yellow.

That's up to the users understanding of what a coral needs. .
Both are actually flawed systems and useless unless you understand what the coral needs not just how much you get on a meter.

Not to take away from the metering teqnique debate. But it's even more interesting that no matter how you measure it. Science is now saying that 350 par is enough. Many users ESP mh are routinely giving in exess of 1500 par and get amazing results. I think that's a much more interesting thing to think about than giving advice to a newb so he stops frying his coral by using a lux meter and begin to understand par.

It is considerably easier to fry corals by using a lux meter than a par meter. I even posted an example of how with the Sicce AM466 review. You can't just say ohh you should have this much lux when you are not taking into account the type of fixture and wavelengths of light involved.

Once again PAR is the photon measurement between 400-700nm measured equally between all the wavelengths. How is a bell curve that sits between 500-600nm even remotely the same? If our lights just had one light source then sure it would be simple to come up with the conversion factor. Two people have a Radion, one runs green channel high with low violet and the other runs almost no green with lots of violet. Same fixture, completely different conversion factor.

 

[gus6464]

@gus6464 Slightly off-topic, do you have pics or something of a blue/lime light. That sounds awesome.

http://www.nano-reef.com/topic/366465-daves-nano-box-drop-off-lagoon-new-start/page-13

All the pics towards the end are with mint. He said he is barely running the white led channel at all. That is all royal blue, mint, cool blue, cyan, and violet. The white channel has warm white and 85CRI neutral white but it's running at less than 5%.

 

[saltyfilmfolks]

It is considerably easier to fry corals by using a lux meter than a par meter. I even posted an example of how with the Sicce AM466 review. You can't just say ohh you should have this much lux when you are not taking into account the type of fixture and wavelengths of light involved.

Once again PAR is the photon measurement between 400-700nm measured equally between all the wavelengths. How is a bell curve that sits between 500-600nm even remotely the same? If our lights just had one light source then sure it would be simple to come up with the conversion factor. Two people have a Radion, one runs green channel high with low violet and the other runs almost no green with lots of violet. Same fixture, completely different conversion factor.

I get all that. I understand light and meters. And spectrum.

But what do you tell the guy who is frying his very precious spent money he probably shouldn't have coral on a hobby he loves dearly and has no money for a par meter
.
If I tell him to use much lower intensity than I know it needs and acclimate watch the corals and be cautious is that really bad advice?

Should only wealthy people be allowed to have corals? That's where we're going with this.

How would you make this more acessable to everyone.

Keep letting them guess? Estimate on what's per gallon? Give pics of thier settings? With no thought of alk and nutrients or flow or the rest of the needed balances when using light ESP higher light?

I prefer to teach. Put a good tool in ther hand a lot of articles and info and put them on the path to learning more about par PUR
And what corals need to thrive.

Thank you.

 

[Brew12]

Like every tool in the tool box, a lux meter has it's uses as long as one understands its limitations. It's real value is in comparative numbers, not necessarily accuracy.
If one person has excellent experience with a specific light, he can share his lux values with someone else who may not have their light mounted at the same height. Then, the 2nd person can replicate his set up by matching lux and lighting ratios. While this may not be exact, it is better than guessing.

If I decide I need to raise my light 5 inches to get better spread I can use a lux meter to measure light before I raise it and then match lux by raising the LED output once it is remounted. Not accurate, but very useful.

Even if the lights are just similar, by sharing lux values that person can typically get in the ballpark of where they need to be. It may not work for exotic lights, but I doubt people using lux meters are getting very exotic with lighting anyway.

Knowing it's limitations, I would much rather use a lux meter and at least have some reference rather than guessing where I am at or spending $400+ on a PAR meter. I'm going to spend that money on a better light!

 

[gus6464]

This hobby is a luxury. To say someone has money to drop hundreds on coral, equipment, etc. but then has no money to spend $200 on a PAR meter makes no sense. Even a Seneye which can be had for less than $200 will give someone who has no clue a much better place to start than a lux meter. I have read a couple of posts you have made where you tell people to shoot for lux in the 50k range. Well what happens when you tell the person with the Sicce light the same thing? He will cook every single coral in that tank and have no clue why.

Another example is with the AP700. Based on your measurements you say it might no do high light corals. When in actuality people who tried to run the thing past 70% were starting to bleach acros.

 

[ksc]

I think the biggest problem with a lux meter, besides being grossly inaccurate, is it measures light outside the tank. I think most people would benefit more by knowing the values inside the tank. I see these meaningless numbers being thrown around, which I assume are the highest numbers recorded outside the tank, directly under the sweet spot. Light can drop off dramatically just a few inches away from an area, especially with these LED setups.

 

[Brew12]

Even a Seneye which can be had for less than $200 will give someone who has no clue a much better place to start than a lux meter.

I thought the Seneye's were not a true Par meter. My understanding is that they are a normal lux meter with a special filter to tune a second lux detector. They then use these two values to calculate both PAR and Kelvin.
Two things I have seen support this. First, is that they claim it will take direct Lux readings but not PAR readings.
Second, they say this:
"We recommend that the seneye PAR function is used only as a measure against light readings taken from other seneye devices or a seneye PAR organism table. Why? most PAR devices are aimed for use in greenhouses where they are more interested in the red end of the PAR spectrum as this is where most terrestrial plant get there useful light from. The seneye device is more sensitive than most at light below 450nm (bluer). This is arguably the most important spectra for coral and why most marine aquarists use additional actinic (03) spectrum bulbs."

From this, it really looks like they are just doing a calculated PAR using a correction factor.

 

[justingraham]

Ok so I'm just a guy who reads threads on this website. (True story)

I know nothing about lights or par pur(that's what a cat does right?) or lux. (Somewhat true now as I have tried to understand the this stuff better)

And as the op said in his original statement there is a lot of talk about lux now in almost every light tread or why is my coral not coloring up or why is it bleaching. (Op good job on starting a thread on it)

Now when I was in the hobby before (4-5 years ago leds just came out) PAR was it there was nothing else maby PUR but def not lux. So when I came back in and started learning again there was a couple people(all have posted in this thread) talking about lux.

Now if I had no background in saltwater before I might be persuaded into going out and "downloading the free lux app on my iPhone" and be ok with that reading and then be left wondering why my corals are not in the best shape. but i didnt and I choose to see what lights worked for other people and used them for now until I can get a par meter. because I personally don't believe lux can help. Unless u have the same exact light as someone. And if u had that why wouldn't u just do the same thing that's working for the other guy.

I haven't great a lux meter because I know that mh are not equal to t5s or to leds or even now u have all three lights combined in hybrids. So why waste 15 dollars on a meter that I will have to end up guessing on anyway.

So as I agree with both sides tho I do I'm not a Lux hater because it's better to have something rather then nothing.

But then I also think what if that something doesn't help u either. So with a Lux meter u now have a number that doesn't mean anything but u do have a number.

Would a lux meter be good at telling u when to change a bulb I think so I could be wrong tho. But would a lux meter help if ur switching from metal halides to leds or whatever we feel like changing to I don't think so.

But to tell a new person setting up a tank that he should be at this Lux with his free iPhone app without completely being there and seeing his set up I feel is kinda irresponsible. Cause he doesn't know any better. So he will set it up just like u said because he's asking a question so chances are he already hasn't looked anything up on the subject so I highly doubt he is going to look into what u tell him to do any further.

Like stated above this is a hobby that is known to be expensive if u have a problem spending 200 dollars or even 300 dollars to ensure ur thousands of dollars of corals is in the proper environment and rather spend 15 dollars or download a free app on at best at guess I think u should rethink the hobby.

What are the most important things in this hobby for keeping coral? Lights flow and water quality. In the grand scheme of things if u want to be in this hobby for a long time what's 2-3 hundred dollars extra on a par meter to make sure ur corals are in the proper environment. Or borrowing one from a fellow hobbyist? No one has a problem dropping money on everything eco tech has or spending 50 dollars for a triton test.


But for light ur going to leave ur corals in the hands of a free app?? I know I am not.

 

[saltyfilmfolks]

It is considerably easier to fry corals by using a lux meter than a par meter. I even posted an example of how with the Sicce AM466 review. You can't just say ohh you should have this much lux when you are not taking into account the type of fixture and wavelengths of light involved.

Once again PAR is the photon measurement between 400-700nm measured equally between all the wavelengths. How is a bell curve that sits between 500-600nm even remotely the same? If our lights just had one light source then sure it would be simple to come up with the conversion factor. Two people have a Radion, one runs green channel high with low violet and the other runs almost no green with lots of violet. Same fixture, completely different conversion factor.

I get all that. I understand light and meters. And spectrum.

But what do you tell the guy who is frying his very precious spent money he probably shouldn't have coral on a hobby he loves dearly and has no money for a par meter
.
If I tell him to use much lower intensity than I know it needs and acclimate watch the corals and be cautious is that really bad advice?

Should only wealthy people be allowed to have corals? That's where we're going with this.

How would you make this more acessable to everyone.

Keep letting them guess? Estimate on what's per gallon? Give pics of thier settings? With no thought of alk and nutrients or flow or the rest of the needed balances when using light ESP higher light?

I prefer to teach. Put a good tool in ther hand a lot of articles and info and put them on the path to learning more about par.

Thank you.

This hobby is a luxury. To say someone has money to drop hundreds on coral, equipment, etc. but then has no money to spend $200 on a PAR meter makes no sense. Even a Seneye which can be had for less than $200 will give someone who has no clue a much better place to start than a lux meter. I have read a couple of posts you have made where you tell people to shoot for lux in the 50k range. Well what happens when you tell the person with the Sicce light the same thing? He will cook every single coral in that tank and have no clue why.

Another example is with the AP700. Based on your measurements you say it might no do high light corals. When in actuality people who tried to run the thing past 70% were starting to bleach acros.

my tank cots 100. My light was 50 at the time. I get free water from the ocean. I can't spend more than 20 on a frag. 75 is pretty scary to me. I've never owned a fish that cost more than 30. The most expensive coral I ever bought was 60 and that was a couple weeks ago and I got an amazing deal and it came with three acro crabs.
Thousands hahahahahajaha ahahaha aha haha ha hah ha

If I sold all my stuff I'd be Lucky to get 500

50k no thats not me. For acro yea. Maybe.