Lux readings

KJoFan

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I've read of many people using the Galactica Luxmeter for iPhone, so I downloaded it and tried it out. At a time when my light was supposed to be at it's peak the best I could muster was 5-5.5k for a reading. I've read that 10k is kind of bare minimum as far as lux at the water surface goes.

This is a Kessil 160 on a Biocube 29. I guess I would have thought the number would be higher than that. I believe the Kessil peaks at 65 or 70% intensity, which I thought would be enough for a tank this size. I have had decline in zoa health and am looking at all possibilities for cause. I also have some zoa/palys that seem to stretch more than they should, which led me to check a little bit into the light levels.

Anyone have any frame of reference or experience with this app? I do realize a dedicated, handheld meter would be more accurate but I was just interested in ballpark.
 

mcarroll

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The app does have to be compatible with the output generated by your camera's light sensor, so it's very possible for an app to work well for some people and not for others.

However, they also have the ability to use BOTH cameras on the phone in most cases – front and back.

Make sure you're doing the reading with the correct camera (on the front).....if you still get low readings, then just try another app or two. If you have a brand new model of phone, try to find one that either claims specific compatibility or one that has at least gotten updated since your phone came out.

I'd order a handheld anyway – for future use. Takes around a couple weeks to ship if you order from China, so doesn't help in the short term.
 

ksc

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Lux meters are terribly inaccurate measuring par and tell you very little about your light levels inside the tank. See if you can find a par meter that you could borrow/rent.
 
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KJoFan

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I was using the correct camera, because i was trying both reflection and direct and sorted out which did which, so I got that part right. :)

Are you looking for a pic to see how far off the water the light is?

This is an older photo but still accurate as far as set up: (it looks in this pic like the light points forward, but it doesn't. It is pointed straight down into the tank using the 90 degree adapter for the Kessil mount.)



I will hunt around for other apps just to do a comparison. Does it seem to you I should be getting a higher lux reading than 5k or maybe that's accurate?
 

saltyfilmfolks

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direct should point at the light. to use reflected put a piece of bright whit paper at the surface and read the paper. its not great but kinda close ish, kinda.

yes you want more than 5 k for sure.


This is the lux meter I have $14 https://www.amazon.com/Docooler-Dig...UTF8&qid=1477324640&sr=8-4&keywords=lux+meter
Maccarol like the one with the hand held attachment $15

If understand the kesil output, you could turn that up to full with no troubles.
Imo on that tank you'd want 25k to 30,000 lux



Lux meters are terribly inaccurate measuring par and tell you very little about your light levels inside the tank. See if you can find a par meter that you could borrow/rent.
By knowing what fixture MH T5 and some Led I'm familiar with, Ive been able to estimate Par on on members tanks within 100 par using lux par conversions without even seeing the tank.
And those members OWN PAR METERS.
inside a par meter is a photovoltaic cell. Inside a lux meter there is also one. we had to invent Fc and Lux meters(100 years ago) to make a Par meter.

fwiw a coral plus conversion number is about 38 according to D riddle and apogee as is a 14k mh
a Kessil is around 55 or so, i think higher
a chinese black box is about 63

If you run conversion numbers 40, 50 and 60 you can get pretty dang close, and learn the relationship between intensity and spectrum and getting good par.

if you own a radion and set it to full on all chanells and use the new Apogee designed for Led, set it next to a lux meter, you can make your own lux par conversion.
then also be bummed out because its probably not nearly as good as T5. 50-55
 

madweazl

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Using the $15 LUX meter on Amazon, at 6.5" (360WE), I measured 12,300 LUX at the lowest intensity and 44,100 LUX at 100% (100% color). The 160 appears to consume roughly 45% (40W vs 90w) less power so I would expect it capable of putting out somewhere around 6700-24,200 LUX. I suspect the phone or app to be the issue.
 

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Using the $15 LUX meter on Amazon, at 6.5" (360WE), I measured 12,300 LUX at the lowest intensity and 44,100 LUX at 100% (100% color). The 160 appears to consume roughly 45% (40W vs 90w) less power so I would expect it capable of putting out somewhere around 6700-24,200 LUX. I suspect the phone or app to be the issue.
good info. thanks!
 

mcarroll

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Are you looking for a pic to see how far off the water the light is?

This is an older photo but still accurate as far as set up: (it looks in this pic like the light points forward, but it doesn't. It is pointed straight down into the tank using the 90 degree adapter for the Kessil mount.)

I will hunt around for other apps just to do a comparison. Does it seem to you I should be getting a higher lux reading than 5k or maybe that's accurate?

Kessil says 1 or 2 lights would be needed for a tank your size, so I would expect it to be on the low side. Unfortunately they don't publish PAR data. (And seems like no users have either...)

Most people are using 360's on 24" cubes though, so I think I'd run your 160 closer to 100% intensity.

Lowering the fixture by half the distance to the water is also a good option and will also effectively double the intensity.

I would use the lux meter to manage the transition though....keep light levels consistent when you make physical changes like to the fixture height. Then after a week or two, turn it up about 2000 lux per week-or-two until you get where you want to be.

Lux meters are terribly inaccurate measuring par and tell you very little about your light levels inside the tank. See if you can find a par meter that you could borrow/rent.
@ksc I see folks reply to lux meter threads with something like that very often, so please forgive the pointed question:

Could you share your experience in using a lux meter on your tank?

I'd try it before you knock it.

Without getting hung up on the theory, it works for quite a few people here on R2R if you care to look. (Some are even using them for underwater measurements!) :)

(site:reef2reef.com success lux is a simplistic search, but good enough to start with...plenty of good comments.)
 

mcarroll

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Using the $15 LUX meter on Amazon, at 6.5" (360WE), I measured 12,300 LUX at the lowest intensity and 44,100 LUX at 100% (100% color). The 160 appears to consume roughly 45% (40W vs 90w) less power so I would expect it capable of putting out somewhere around 6700-24,200 LUX. I suspect the phone or app to be the issue.


Double-down what I just said. :D
 
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KJoFan

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I am going to try increasing the intensity slowly. The controller only goes in 5% increments so I'll bump it up by 5% every week or two. With the way it mounts to the biocube (not that well) and the gooseneck being fairly difficult to manipulate I'll leave it as it is physically for now and see if increasing intensity works. It may be that I'll need to also lower it closer to the water as well. Or, I could upgrade to a 360 which should get me some good mileage in increasing intensity.

I realize the app luxmeters are probably not something to live and die by, but honestly I am only looking for approximate values to see if my lighting intensity is reasonable or needs some adjustment. I feel the app at least gives me something to go off of.
 

ksc

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Kessil says 1 or 2 lights would be needed for a tank your size, so I would expect it to be on the low side. Unfortunately they don't publish PAR data. (And seems like no users have either...)

Most people are using 360's on 24" cubes though, so I think I'd run your 160 closer to 100% intensity.

Lowering the fixture by half the distance to the water is also a good option and will also effectively double the intensity.

I would use the lux meter to manage the transition though....keep light levels consistent when you make physical changes like to the fixture height. Then after a week or two, turn it up about 2000 lux per week-or-two until you get where you want to be.


@ksc I see folks reply to lux meter threads with something like that very often, so please forgive the pointed question:

Could you share your experience in using a lux meter on your tank?

I'd try it before you knock it.

Without getting hung up on the theory, it works for quite a few people here on R2R if you care to look. (Some are even using them for underwater measurements!) :)

(site:reef2reef.com success lux is a simplistic search, but good enough to start with...plenty of good comments.)
I've never bothered using a lux meter to measure par. I've had par meters for years. I do know from testing over 100 tanks that waving a wand over the surface, par meter, lux meter, etc. , is a very poor way to measure par INSIDE the tank. There are all kinds of variables that affect the light that each individual coral receives. Now start with some gizmo that is known to perform poorly measuring par, you can pretty much toss those results and just guess....
 

saltyfilmfolks

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I am going to try increasing the intensity slowly. The controller only goes in 5% increments so I'll bump it up by 5% every week or two. With the way it mounts to the biocube (not that well) and the gooseneck being fairly difficult to manipulate I'll leave it as it is physically for now and see if increasing intensity works. It may be that I'll need to also lower it closer to the water as well. Or, I could upgrade to a 360 which should get me some good mileage in increasing intensity.

I realize the app luxmeters are probably not something to live and die by, but honestly I am only looking for approximate values to see if my lighting intensity is reasonable or needs some adjustment. I feel the app at least gives me something to go off of.
I think youll be happier.

Imo, you can pretty safely move corals up to the rocks as well know that you know your light range.

if you upgrade, the real lux may be something to look at.
 

ksc

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If you're looking to upgrade your lux meter, this is available on ebay...

s-l1600.jpg
 

madweazl

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Our local group has a PAR meter that makes its rounds but there are a number of people ahead of me still. I did try a phone app (called LUX METER) and it was very consistent with the cheap meter from Amazon (phone is a Galaxy S7 Edge).
 

saltyfilmfolks

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I've never bothered using a lux meter to measure par. I've had par meters for years. I do know from testing over 100 tanks that waving a wand over the surface, par meter, lux meter, etc. , is a very poor way to measure par INSIDE the tank. There are all kinds of variables that affect the light that each individual coral receives. Now start with some gizmo that is known to perform poorly measuring par, you can pretty much toss those results and just guess....
understood. Imo its easy to get bad readings on both meters.
I do like to promote lux as an understanding of par, as it is a component. by calculating its not exactly guessing its estimating. try my math, its pretty close.

I will say chasing 30 par for a coral, i believe is chasing numbers.

and fwiw esp now with led most people are guessing. Id like to see that end, and use both as learning tools.

DID you know that in the old days for film, Directors of photography and Gaffers(lighting directors), the guys who meter light, HAD to wear black. A white shirt will throw of your readings by a half stop.
Now we use a monitor and analyzer to break down the light into rgb and measure the values of each hitting the object(sound familiar?). We now understand that a half stop is nothing.

I encourage the use and understanding of both lux and par meters.
On some movies they can only afford for me to use my hand held meters and eye, on some movies I get the full $$$$$$$ monitor and analyzers.
On most movies you ever watched, they had not yet invented those monitors and analyzers.
 

mcarroll

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Our local group has a PAR meter that makes its rounds but there are a number of people ahead of me still. I did try a phone app (called LUX METER) and it was very consistent with the cheap meter from Amazon (phone is a Galaxy S7 Edge).

When you finally get the par meter, compare your measurements between the two meters and you have yourself an accurate conversion factor for your specific lights. (Lux / PAR = conversion factor)

Apogee and Dana Riddle have both (separately) published a few conversion factors just for reference.
 

mcarroll

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(A conversion factor is not necessary to use a lux meter though. It's mostly necessary if you want to directly compare measurements with somebody. Assuming a generic conversion factor of 50 works for me. It does not appear that the conversion factors very more than from 30 to 70 even with extremely non-reef like lighting. Most reef lights seem to get a conversion factor pretty close to 50. 50 would literally be the conversion factor for sunlight.)
 
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