LUX meter: How is it Useful?

[john.m.cole3]

I have taken the recommendation from @mcarroll and @saltyfilmfolks and bought a handheld LUX meter. I know it measure brightness at the water line and can help you find the high and low spots of light for placing your corals... but could you guys help explain WHAT lux is and how it is relevant in our aquariums. I need more information to help educate other members on my reef club. Right now, my highest LUX reading is 47,000 in the middle of my tank. Thanks for the guidance fellas!

 

[Sabellafella]

Ive acually seen people map out a tank with lux. The measurements are almost spot on with par BUT these people have ben doing this forever and have a good feel as to how to use one. its different for every single light/build/fixture/led. Personally its useless for me, but im sure i can learn. You need to measure it against par anyway to get an accurate feel on it. I guess i just see it differently. Ive bleached and nearly killed numerous corals from a +/- in 10-20 par difference. And that is darn near impossible to accurately measure that with a lux meter

Btw 50,000 lux in the middle of the tank is acually a whole lot if light, somewhere from 300 to 500 par

 

[john.m.cole3]

YEah that reading is about 1 inch off water line w/ 2x blue+, actinic, and purple + @ 70% and 2x coral+ @35%

 

[saltyfilmfolks]

Ive acually seen people map out a tank with lux. The measurements are almost spot on with par BUT these people have ben doing this forever and have a good feel as to how to use one. its different for every single light/build/fixture/led. Personally its useless for me, but im sure i can learn. You need to measure it against par anyway to get an accurate feel on it. I guess i just see it differently. Ive bleached and nearly killed numerous corals from a +/- in 10-20 par difference. And that is darn near impossible to accurately measure that with a lux meter

Btw 50,000 lux in the middle of the tank is acually a whole lot if light, somewhere from 300 to 500 par

Hmmmm plus or minus 10 and 20. We'll have to talk about that one later

And according to Dana r calculations 50000 lux. with t5 can be closer to 1000 par.

 

[Sabellafella]

Hmmmm plus or minus 10 and 20. We'll have to talk about that one later

And according to Dana r calculations 50000 lux. with t5 can be closer to 1000 par.

Yea its crazy no? Mostly favias/favites leptos montis cyphastrea platygyre.

 

[saltyfilmfolks]

:):)

Ive acually seen people map out a tank with lux. The measurements are almost spot on with par BUT these people have ben doing this forever and have a good feel as to how to use one. its different for every single light/build/fixture/led. Personally its useless for me, but im sure i can learn. You need to measure it against par anyway to get an accurate feel on it. I guess i just see it differently. Ive bleached and nearly killed numerous corals from a +/- in 10-20 par difference. And that is darn near impossible to accurately measure that with a lux meter

Btw 50,000 lux in the middle of the tank is acually a whole lot if light, somewhere from 300 to 500 par

IMO lux is a cheaper more accessible meter mainly. 15 to 75 bucks.
Esp for many just starting out.
If you weren't thinking in par you would think only in intensity. It actually is a bit simpler to comprehend.

Outside on a nice day is 100,000 lux.
In the dark is 0 lux.
Experience has tauht us on a 24 in tank 15 to 50,000 lux will grow corals depending on species.
Yea pretty much any light source. It's been tried.

Same can be said for orchids actually and other agriculture and plants

Though they generally use foot candles not lux. Jus another standard of light intensity. Metric and English

If using a light with spectral properties that are know to grow a specific plant or coral. You now need to know how much of that light you need.

How much measured intensity in lux or foot candles.

Good Spectrum plus intensity can be measured by a par meter.

But

Good light for green beans and a high light SPS coral are spectrally very different.
But both can be lets say 750 par.

Thus my new found preference of choosing lighting color species specifily and measure its intensity.

But like so many thing in Reefing. It all works.

I'm not at home right now. Actually color timing a film. Kinda cool. But I'll look for a few of the convos that we've had that are good. And I highly reccomend research and experimentation hands on. There's distict difference in learning by doing and reiteration of teqnique one has simply read. Or been told.
Example.
Many folks have so often said you cannot convert lux to par.
That's kinda weird especially if one were to actually look there is a lux to par conversion chart right on the bigges name in par meters website.
I would not have known that if I had not looked for myself.
And than used a meter on my tank. And the dt at the Lfs.
:)

My homework next week is to take tank pics and start a lux article. Wish me luck

 

[saltyfilmfolks]

Yea its crazy no? Mostly favias/favites leptos montis cyphastrea platygyre.

Gotta take mental note. On that one.

 

[john.m.cole3]

:):)


IMO lux is a cheaper more accessible meter mainly. 15 to 75 bucks.
Esp for many just starting out.
If you weren't thinking in par you would think only in intensity. It actually is a bit simpler to comprehend.

Outside on a nice day is 100,000 lux.
In the dark is 0 lux.
Experience has tauht us on a 24 in tank 15 to 50,000 lux will grow corals depending on species.
Yea pretty much any light source. It's been tried.

Same can be said for orchids actually and other agriculture and plants

Though they generally use foot candles not lux. Jus another standard of light intensity. Metric and English

If using a light with spectral properties that are know to grow a specific plant or coral. You now need to know how much of that light you need.

How much measured intensity in lux or foot candles.

Good Spectrum plus intensity can be measured by a par meter.

But

Good light for green beans and a high light SPS coral are spectrally very different.
But both can be lets say 750 par.

Thus my new found preference of choosing lighting color species specifily and measure its intensity.

But like so many thing in Reefing. It all works.

I'm not at home right now. Actually color timing a film. Kinda cool. But I'll look for a few of the convos that we've had that are good. And I highly reccomend research and experimentation hands on. There's distict difference in learning by doing and reiteration of teqnique one has simply read. Or been told.
Example.
Many folks have so often said you cannot convert lux to par.
That's kinda weird especially if one were to actually look there is a lux to par conversion chart right on the bigges name in par meters website.
I would not have known that if I had not looked for myself.
And than used a meter on my tank. And the dt at the Lfs.
:)

My homework next week is to take tank pics and start a lux article. Wish me luck

I wish you lux, LOL

 

[saltyfilmfolks]

https://www.reef2reef.com/threads/confuse-about-intensity-and-spectrum.231543/#post-2705803

https://en.wikipedia.org/wiki/Lux

http://www.apogeeinstruments.com/conversion-ppf-to-lux/
note. They dont list reef spectrums under halide.



Simply
Lux = how much
Conversion constant= how good a light
Par=how much is useful

47,000 lux from sun, divide by constant(57 from apogee)=824 par

A conversion factor (constant) is derived mathematically by using a lux meter and a par meter.



constant of ;
t5 14k 46
chinese led 60(IME estimate)
MH 20k 57

SO
if you take a coral from the sun @47k lux to a mh blue at 80,000 k lux it will burn.

If you take a coral from the store under chinese led @ 47k lux and put it under t5 @ 47k lux it will burn

If you replace your t5 @ 47k lux with a MH Blue, you can now est the reduction in Par/lux for acclimation:)

If you ask folks about thier light setting and they say 60% you can now be confused too.:confused:

Bottom line message becomes, Light, in par or lux is just another parameter that can be tested.

But I suppose I could eyeball my Alk too.o_O


Hope this is a good start. Trying to keep it simple here.
Led gets complicated.

 

[saltyfilmfolks]

@john.m.cole3

 

[Tbabcock]

I would like to know how we take the measurements. The cheaper meters are not water proof so how does this work, from the front glass? Or do you place them in a large clear plastic bag or something to submerge the unit to different depths of the tank?

 

[saltyfilmfolks]

I would like to know how we take the measurements. The cheaper meters are not water proof so how does this work, from the front glass? Or do you place them in a large clear plastic bag or something to submerge the unit to different depths of the tank?

just meter the top. if its a deep tank then be more concerned. only slightly though really.

or buy a waterproof one if your really curious. you can also test dry. ie point light at meter 36in away(bottom of tank). water and glass dont cut light that much. Ime.
fwiw though, different light sources do have different "falloff" how fast the light is dispersed as it leaves the lamp.
that is also easily tested dry. my Current orbit is like that.FAST fall off.

http://www.testequipmentdepot.com/products.htm?item=MW700&ref=gbase&gclid=CMr065WYvMwCFVE0aQodi2cFWA
$56.66 for a Milwaukee w waterproof probe.(2 second google search)

Hmmm says for aquariums right on it. Kinda weird "they" say it doesn't exist.:confused:

 

[alton]

For 12 years I used a Foot candle meter to tell me when to change my lamps or check my leds for drop off. I check them on day 1 and then every month take a spot check and when the footcandles drop by 10% change the lamps. I actually had two led fixtures replaced because they dropped by 50% in a year. I also had a PAR meter to use in the last 3 years and the drop off between PAR and foot candles has been fairly close.

 

[saltyfilmfolks]

I would like to know how we take the measurements. The cheaper meters are not water proof so how does this work, from the front glass? Or do you place them in a large clear plastic bag or something to submerge the unit to different depths of the tank?

I hit mine just from the top. I know for a fact light gets to the bottom. If I think I need more light for the stuff on the bottom(browning), Im going to turn up the lights.
and yes you can just put it in a bag if your curious. the milwaukee is $75 for a waterproof meter.

 

[saltyfilmfolks]

I used a Foot candle meter

difference between metric and english really.