Why all the talk about LUX?

[gus6464]

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.

I own a Seneye and have taken measurements on it against an Apogee MQ-200 and they are pretty much the same. BRS has also done this and got to the same conclusion. Regardless there are 3 meters out there under $200. Biotek BTM-3000 and Apogee SQ-420 which are the same thing really and the Seneye. Then if you already have a multimeter you can get the new SQ-500 for $295 which measures better and blueacro sells a little pcb converter that you plug into the multimeter if you don't want to do the math for cheap.

 

[saltyfilmfolks]

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.

Yea don't use the app. I don't reccomend it. Cameras work differently than a meter

My lightbulb moment came from reading articles. Article after article And then old old old threads. Lux is what they used to do in the Olden days before par meters and when they were reall really expensive.
The overall recommendation was to have at least 3000 lux on the sand.
Par IMO is just the progression of the science and still useful

You've read my stuff friend. I never blindly reccomended levels. It's all about acclimation and understanding what different corals need. I regularly admit it.

Well written comment. Thank you.

 

[saltyfilmfolks]

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.

The counter point is if you place the par probe next to a rock or registers as lower par. More on the sand. If you meter the top and the wall is white you get a higher par reading too.
The ball is round so it's considered an ambient meter. It registers the area around the subject and that's useful.
Theres both flat and round discs on photo meters for this same reason. To avoid or only read Ambient or incedent light readings.

Im actually surprised PAR meters use a ball kind but not really because I know what the meter is looking for.

And fwiw any light meter including par will read light from outside the tank. Is has to its physics.

Both are flawed. Lux and par. ESP if your chasing numbers.

 

[ksc]

There isn't really a counter point, because you can't measure inside the tank with those cheapo lux meters. So the point is, par meters give a pretty good reading inside the tank whereas luxsux......

 

[Sabellafella]

Some good stuff here. I never fully understood lux, but the #1 (other then basics) aspect of growing any type of photosynthetic coral is lighting, and i recommend everyone to get a par meter especially if your spending a pretty penny on the hobby. Laymens terms, a par meter is my test kit for my lighting. I say this every time lux or par pops up in the equation, you can bleach a coral under certain lighting just from moving it 2 inches from its previous spot. Wether or not you have to buy it is up to you, my lfs lets me rent theirs for 20 dollars a year, anytime i need to use it ill go pick it up. Im sure everyone can go to a local club or split the difference to get one. In my opinion, Anyone that uses bulbs should own a par meter. leds you can litterally borrow one, take some measurments and your good to go.

 

[gus6464]

Don't really understand why you keep putting a lux meter in the same so called "flawed" level as a PAR meter when their level of inaccuracy is not even remotely close.

Saying this

Is as flawed as this

Is quite ridiculous. The baseline for errors with a lux meter is orders of magnitude greater than a par meter. Unless there is a conversion factor that goes with every lux number recommendation for the specific light unit and spectrum the person is asking about, all those lux numbers are just random and mean absolutely nothing. Pretty much every single LED light out there has multiple different color diodes so you can't just give out a blanket lux conversion because the spectrum differences within the same light will yield a completely different conversion factor. 25K lux for two people using the same exact light is not the same unless they are both also using the same identical spectrum. PAR doesn't have this limitation. 400 PAR in a 10K light is still 400 PAR in a 20K light.

 

[gus6464]

The irony in all of this is that if there are two types of lighting in which a lux meter is actually useful to get a quick reading it's metal halide and T5. Bulbs are all the same so once you have a conversion factor you are set. But the irony comes in that MH and T5 are considerably easier to eyeball a hanging distance that most don't need meters. LEDs which really need these meters as the spectrum they put out is all different becomes a real pain when trying to get a conversion.

 

[saltyfilmfolks]

There isn't really a counter point, because you can't measure inside the tank with those cheapo lux meters. So the point is, par meters give a pretty good reading inside the tank whereas luxsux......

Ah got it. What a Good point you make there
A submersible Milwaukee would be bad too or any submessable light meter that uses the lux standard wouldn't work.
Sorry. I totally see your point.
Very scientific.

 

[justingraham]

Yea don't use the app. I don't reccomend it. Cameras work differently than a meter

My lightbulb moment came from reading articles. Article after article And then old old old threads. Lux is what they used to do in the Olden days before par meters and when they were reall really expensive.
The overall recommendation was to have at least 3000 lux on the sand.
Par IMO is just the progression of the science and still useful

You've read my stuff friend. I never blindly reccomended levels. It's all about acclimation and understanding what different corals need. I regularly admit it.

Well written comment. Thank you.

Yes I have read ur stuff and I was not talking about u. But as u comment in most of those threads u know who I speak of and that's fine because that is their belief.

Look it's like someone said it's a way to test their lights like we test our water.
But to me I rather get the best test kit instead of the cheaper one.

Some people don't have the money and I umdestand that as well. Some people just want to throw stuff in a tank because they enjoy that and I fully respect that as well. This hobby works that way as well.

To me this hobby gives u what u put into it.

And although some of the best tanks i have ever seen are simple in a lot of aspects but I bet at one point or another those simple tanks have used a par meter at least once.

 

[saltyfilmfolks]

Yes I have read ur stuff and I was not talking about u. But as u comment in most of those threads u know who I speak of and that's fine because that is their belief.

Look it's like someone said it's a way to test their lights like we test our water.
But to me I rather get the best test kit instead of the cheaper one.

Some people don't have the money and I umdestand that as well. Some people just want to throw stuff in a tank because they enjoy that and I fully respect that as well. This hobby works that way as well.

To me this hobby gives u what u put into it.

And although some of the best tanks i have ever seen are simple in a lot of aspects but I bet at one point or another those simple tanks have used a par meter at least once.

Well said sir. I feel you.
A par meter is the best way to meter for what we're looking for. Yes I want one.
We do what we can to follow our passion.

And no. Some people have no idea there is such a thing as a par meter.
Some still ask me about watts per gallon.
Some use the app and say they get 234437 lux and it must be right.
No. I've never used a par meter on my tank
But it's pretty nice I think. For a bunch of hitchiker coral $5 frags and rescue frags.

Most everything I have I grew.

Yea i know.
I need more zoas

 

[mcarroll]

That's where we're going with this.

Gus is there every time I see him. Sometimes with backup!

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

You would be interested to look up some threads on DIY PAR meters. See what it takes to literally turn a lux meter into a PAR meter.

Yes I have read ur stuff and I was not talking about u. But as u comment in most of those threads u know who I speak of and that's fine because that is their belief.

You may as well name names instead of being coy. What is this all of a sudden, high school or something? Who?

You guys are all done some great follow ups. It's a little crazy how repetitive this discussion is. Going back to my original comment, it's being caught up in the theory versus trying it out or paying attention to the folks who've been using it for years. It's neither as simple nor as complicated as detractors are putting great efforts into painting it.

After all that's been said, that a few folks can still come away with nothing but they thought that someone said you should only use a lux meter or that a PAR meter is bad or any of the other ridiculous things that have been said...it is a little bit...hm.

Anyway, keep it up y'all.

 

[Hans-Werner]

Gus,

excellent explanations! It is very easy to explain why measuring lux is quite useless when you show the repsonse curve of a luxmeter. It is also the cause why manufacturers can offer "high lumen illumination", just add a large peak around 555 nm wavelength and you will have more lumen output at the same output in mW or PAR. It is much easier to create a lighting with higher lumen output than a lighting with higher mW or PAR output. The one just needs to concentrate the output a bit more to the 555 nm wavelength, the other needs a better conversion of current to (PA)radiation.
Here is also a good explanation using the response curve of the human eye and of plants.

 

[saltyfilmfolks]

Gus,

excellent explanations! It is very easy to explain why measuring lux is quite useless when you show the repsonse curve of a luxmeter. It is also the cause why manufacturers can offer "high lumen illumination", just add a large peak around 555 nm wavelength and you will have more lumen output at the same output in mW or PAR. It is much easier to create a lighting with higher lumen output than a lighting with higher mW or PAR output. The one just needs to concentrate the output a bit more to the 555 nm wavelength, the other needs a better conversion of current to (PA)radiation.
Here is also a good explanation using the response curve of the human eye and of plants.

http://www.advancedaquarist.com/2008/2/review

 

[chema]

Gus, thanks for an excellent explanation, not only of the differences in measuring light but when highlighting (!) how inaccurate is to use lumens with respect to LED fixtures.

 

[chema]

http://www.advancedaquarist.com/2008/2/review

I don't see any LED fixture in the list of light sources provided to show different lux to PAR conversion factors

 

[ksc]

http://www.advancedaquarist.com/2008/2/review

This about sums up what I've been saying. Measuring light outside the aquarium is a very poor indicator of what is inside the tank. Now take measurements with a device known to be highly inaccurate, and your results are pretty much worthless.

"Hobbyists using a light-measuring device for the first time will probably be surprised at how rapidly the light field can change within an aquarium."

 

[saltyfilmfolks]

I don't see any LED fixture in the list of light sources provided to show different lux to PAR conversion factors

It's in a different article by the same author.

 

[FlintTownReaper]

Yea don't use the app. I don't reccomend it. Cameras work differently than a meter

My lightbulb moment came from reading articles. Article after article And then old old old threads. Lux is what they used to do in the Olden days before par meters and when they were reall really expensive.
The overall recommendation was to have at least 3000 lux on the sand.
Par IMO is just the progression of the science and still useful

You've read my stuff friend. I never blindly reccomended levels. It's all about acclimation and understanding what different corals need. I regularly admit it.

Well written comment. Thank you.

A. The apps dont use the camera. They use the light sensor that the software then uses for the camera ISO auto adjustment.

B. "The olden days"is also a time period when almost all reef aquarists were using similar bulbs, either incandecent or hallide 6500K lighting so saying 3000 lux at the sandbed was an easily comparable statement tabk to tank. Todays technology simply makes LUX and nearly useless measurement as even fixture to fixture some quality defects, tank particulate, even salt concentration can effect LUX levels. Let alone as previously stated many times, the simple lower end of spectrum where lux diminishes and PAR/PUR rockets upward in measureable values.

 

[Hans-Werner]

I use several cheap luxmeters myselft as substitute for PAR measurements but only in my greenhouse and on my window sills. Natural daylight has always an even and similar spektrum. But you just can´t compare a Royal Blue LED with a white LED using a luxmeter except you have an exact conversion factor for both. But even then I would doubt that a cheap luxmeter follows the norm lux response curve precise enough that you have meaningful numbers in the end.
For aquaria and artificial lighting I prefer the PAR measurement, for example with a Apogee PAR meter.

 

[saltyfilmfolks]

This about sums up what I've been saying. Measuring light outside the aquarium is a very poor indicator of what is inside the tank. Now take measurements with a device known to be highly inaccurate, and your results are pretty much worthless.

"Hobbyists using a light-measuring device for the first time will probably be surprised at how rapidly the light field can change within an aquarium."

You can get one that goes in the aquarium if your curious. Or put it in a ziplock bag or get one designed to go in the ocean. They make those.


Most people who use any light meter of any type are surprised at how rabpidly light fields change any where at any time of day Fromm room to room. From fixture to fixture too depending on the design.
You should actually try it.
I have for 25 years. In snow water rain swimming pools forests stages deserts city's buildings slums and aquariums.

He also says the lux meter is ok as it's cheaper but not as accurate in many ways and has limitations like all of us lux meter users also say. And have from the beginning of this thread.

I find see where he said it was usless.

You won't give an inch because you don't know anything else.
We all understand a par meter.
Your camp clearly does not understand light meters.
You definitely do understand not having access to one.

None here have come forward with a better way at to teach and understand how to explain how to set a light on a tank without guessing besides getting something they can't afford or find or borrow.
We have. It is not ideal. It is not entirely accurate. But it works.

That is an article by an actual expert who says it works but has limitations that we all accept and also explain that same thing to people on a daily basis but you won't set aside Whatever your issues are to accept th scientific fact.

In a forum so accepting of any and all types of reefing from canisters to aquaclears I find it mind blowing the dissent and near ridicule in this thread to the use of a simple tool to educate people on how light works.
Intensity. Spectrum.

You are welcome to believe that a difference in 14 par wilnkill your coral and I will gladly
Let you run your tank that way. People chase ph and everybody say not to so you can chase yours. How about you let us chase ours. I can use an API test kit if I want to. If I get the full salifert one day great. Right now it's what we got.

I'm sure there's a problem with salifert too if I post a thread on it.

Ok actual ridicule. That's still got me pretty steamed. It not what we see here or do or how we behave here. So a discussion about meters devolves into this?
Well done sirs Well done.