Par to lux conversion - real world T5 numbers

[Scott.h]

There are always debates going on on how to convert lux into par.. What the real conversion factors are. What's lost in the blue spectrum conversion, how much par do lights actually produce, etc. I struggled with this for a long time before finally breaking down and buying a good par meter. The reason is, obviously, because good par meters are expensive, and lux meters can be had for a few bucks. But LUX can be converted, even with that possible error factor it's better then nothing. But I thought I would take the time to show some real world numbers for those who have lux meters and are curious, or for those trying to convert lux to par because they don't have access to a par meter.

This is a new tank build, and there has been carbon running in the water via reactor for a month, so the water probably won't get any clearer than what it is here.

The PAR meter used is the new apogee MQ 500. (Said to be more accurate in the lower end of the spectrum because of the new "blue" and LED world we are in)

The LUX meter used is the Milwaukee MW 700 with waterproof probe. Both new and calibrated.

The lighting used is a new 54 Watt 8 bulb ATI sun power T5, dimmable. Running 100%, both channels. The bulbs are brand new and have been running in for about 2 hours.

ATI bulbs used, in order:

Blue plus
Coral plus
Attinic
Aqua blue special
Blue plus
Purple plus
Coral plus
Blue plus

(FYI for those curious, the purple and attinic are Channel one for now, as pictured)

I'm pretty impressed with this fixture. The bottom of the fixture is 9 inches above the top of the tank. Hopefully this distance will keep salt splash residue to a minimum.

Readings at the top of the tank, but out of the water. 9" - 41200 lux - 862 par

In the water:
2" - 23000 lux - 560 par
6" - 20000 lux - 410 par
12" - 132000 lux - 325 par
16" - 18000 lux - 300 par
24.5" - 9500 to 1100 lux - 225 to 260 par
Bottom (variation because of the rocks).

I currently have four different systems running. I'm slowly changing back to T5. For this soon to be, dominate SPS tank, I feel I can have better success, better coverage, and quite frankly it's cheaper up front. Also it's built inside of the wall so I'm not concerned about it being an eyesore.

I'll say that the T5 lighting doesn't lose nearly as much PAR depth wise than the LEDs that I have. I'm going to let these burn in for three days, and turn them down to where I'm hopefully around 400 par at the water surface, and 100 on the bottom. For the corals that I'm going to keep in here that should do just fine.

And as the saying goes, it's better to have it and not need it, then to need it and not have it.

 

[Scott.h]

@saltyfilmfolks .. You asked to tag you when I got this going

 

[saltyfilmfolks]

@saltyfilmfolks .. You asked to tag you when I got this going

Thanks Scott!

 

[saltyfilmfolks]

The PAR meter used is the new apogee MQ 500. (Said to be more accurate in the lower end of the spectrum because of the new "blue" and LED world we are in)

Jealous

The LUX meter used is the Milwaukee MW 700 with waterproof probe. Both new and calibrated.

Jealous

The lighting used is a new 54 Watt 8 bulb ATI sun power T5, dimmable. Running 100%, both channels.

Still jealous.

Readings at the top of the tank, but out of the water. 9" - 41200 lux - 862 par

45 conversion

16" - 18000 lux - 300 par

also 45

Deciding on a lux level is similar to deciding on Par level. youll have to do some research.
According to Apogee and D riddle there are some easy conversion numbers.
The sun is 53(I use 50 just for ease)
bluer Mh and T5 seem to fall in the 50 conversion as well
t5 and some MH in the 10,to 14k range run in the 40 range
From My and D riddle I have observed LED to be 60.

So
warm T5 Mh 40
Blue MH t5 sun 50
Led 60

So if Daniel has 18,000 lux on his led, divide by 60 300 par.

I have on my 55g, 40,000 lux so 600 par.
If i have a question on it I run the same number 40k / 50, or 40k by 55. its usually in the ball park
I personally have not yet seen an led that gets better than 60 as a conversion number.(save "white" only but nothing conclusive)

I wrote this 5 min ago
https://www.reef2reef.com/threads/light-meter.281052/#post-3416300
Deciding on a lux level is similar to deciding on Par level. youll have to do some research.
According to Apogee and D riddle there are some easy conversion numbers.
The sun is 53(I use 50 just for ease)
bluer Mh and T5 seem to fall in the 50 conversion as well
t5 and some MH in the 10,to 14k range run in the 40 range
From My and D riddle I have observed LED to be 60.

So
warm T5 Mh 40
Blue MH t5 sun 50
Led 60

So if Daniel has 18,000 lux on his led, divide by 60 300 par.

I have on my 55g, 40,000 lux so 600 par.
If i have a question on it I run the same number 40k / 50, or 40k by 55. its usually in the ball park
I personally have not yet seen an led that gets better than 60 as a conversion number.(save "white" only but nothing conclusive)

 

[ksc]

Did you add 30% to the underwater par numbers? That's quite a drop off from the water surface to 2" under.

 

[gus6464]

There are always debates going on on how to convert lux into par.. What the real conversion factors are. What's lost in the blue spectrum conversion, how much par do lights actually produce, etc. I struggled with this for a long time before finally breaking down and buying a good par meter. The reason is, obviously, because good par meters are expensive, and lux meters can be had for a few bucks. But LUX can be converted, even with that possible error factor it's better then nothing. But I thought I would take the time to show some real world numbers for those who have lux meters and are curious, or for those trying to convert lux to par because they don't have access to a par meter.

This is a new tank build, and there has been carbon running in the water via reactor for a month, so the water probably won't get any clearer than what it is here.

The PAR meter used is the new apogee MQ 500. (Said to be more accurate in the lower end of the spectrum because of the new "blue" and LED world we are in)

The LUX meter used is the Milwaukee MW 700 with waterproof probe. Both new and calibrated.

The lighting used is a new 54 Watt 8 bulb ATI sun power T5, dimmable. Running 100%, both channels. The bulbs are brand new and have been running in for about 2 hours.

ATI bulbs used, in order:

Blue plus
Coral plus
Attinic
Aqua blue special
Blue plus
Purple plus
Coral plus
Blue plus

(FYI for those curious, the purple and attinic are Channel one for now, as pictured)

I'm pretty impressed with this fixture. The bottom of the fixture is 9 inches above the top of the tank. Hopefully this distance will keep salt splash residue to a minimum.

Readings at the top of the tank, but out of the water. 9" - 41200 lux - 862 par

In the water:
2" - 23000 lux - 560 par
6" - 20000 lux - 410 par
12" - 132000 lux - 325 par
16" - 18000 lux - 300 par
24.5" - 9500 to 1100 lux - 225 to 260 par
Bottom (variation because of the rocks).

I currently have four different systems running. I'm slowly changing back to T5. For this soon to be, dominate SPS tank, I feel I can have better success, better coverage, and quite frankly it's cheaper up front. Also it's built inside of the wall so I'm not concerned about it being an eyesore.

I'll say that the T5 lighting doesn't lose nearly as much PAR depth wise than the LEDs that I have. I'm going to let these burn in for three days, and turn them down to where I'm hopefully around 400 par at the water surface, and 100 on the bottom. For the corals that I'm going to keep in here that should do just fine.

And as the saying goes, it's better to have it and not need it, then to need it and not have it.

Is the Apogee data logger the new one that already takes into account immersion effect of 33% or the old one?

 

[saltyfilmfolks]

Did you add 30% to the underwater par numbers? That's quite a drop off from the water surface to 2" under.

Im still unclear as to why they add 30% to a probe 2in below and 24in below? Do you know why? diffusion should be an increasing number with increase of depth, No?

 

[gus6464]

Nvm the new data logger has a blue face on it instead of yellow so the readings need an increase of 30% when underwater if you already didn't take that into account.

 

[ksc]

Im still unclear as to why they add 30% to a probe 2in below and 24in below? Do you know why? diffusion should be an increasing number with increase of depth, No?

I have no idea. I just go by what Apogee says. Here's the "White Paper"...

http://www.apogeeinstruments.com/co...ection-Factors-for-Apogee-Quantum-Sensors.pdf

 

[Scott.h]

Jealous

Jealous



Still jealous.



45 conversion

also 45

I wrote this 5 min ago
https://www.reef2reef.com/threads/light-meter.281052/#post-3416300
Deciding on a lux level is similar to deciding on Par level. youll have to do some research.
According to Apogee and D riddle there are some easy conversion numbers.
The sun is 53(I use 50 just for ease)
bluer Mh and T5 seem to fall in the 50 conversion as well
t5 and some MH in the 10,to 14k range run in the 40 range
From My and D riddle I have observed LED to be 60.

So
warm T5 Mh 40
Blue MH t5 sun 50
Led 60

So if Daniel has 18,000 lux on his led, divide by 60 300 par.

I have on my 55g, 40,000 lux so 600 par.
If i have a question on it I run the same number 40k / 50, or 40k by 55. its usually in the ball park
I personally have not yet seen an led that gets better than 60 as a conversion number.(save "white" only but nothing conclusive)

I think you're definitely pretty darn close. Back when I was trying to convert Lux I wasn't changing the formula from led to t5. I think I was using 55 or 57 across the board. So when I started playing with the t5 numbers I knew something couldn't be right. That's when I broke down and bought the par meter. It makes sense now.

Did you add 30% to the underwater par numbers? That's quite a drop off from the water surface to 2" under.

I have the MQ not the SQ. Those are the numbers read right off the meter. I talked to apogee direct before I bought the meter. He knew exactly what I was doing with it, and this is the meter he told me to get. He never said anything about converting anything under water, so I'd be surprised if I need to. I'll have to call them next week to verify.

 

[ksc]

I have the same meter. You need to add 32% to those underwater readings.
http://www.apogeeinstruments.com/underwater-par-measurements

 

[saltyfilmfolks]

I think you're definitely pretty darn close. Back when I was trying to convert Lux I wasn't changing the formula from led to t5. I think I was using 55 or 57 across the board. So when I started playing with the t5 numbers I knew something couldn't be right. That's when I broke down and bought the par meter. It makes sense now.

I have the MQ not the SQ. Those are the numbers read right off the meter. I talked to apogee direct before I bought the meter. He knew exactly what I was doing with it, and this is the meter he told me to get. He never said anything about converting anything under water, so I'd be surprised if I need to. I'll have to call them next week to verify.

funny he didnt mention it.
But the take away from the white paper is yes, there's a .33 average difference in light transmission in water and air due to refraction..
so the conversion would apply to both meters.

Back when I was trying to convert Lux I wasn't changing the formula from led to t5. I think I was using 55 or 57 across the board.

yup. and most don't or wont do a Lux Par conversion on led...Yet

 

[Scott.h]

funny he didnt mention it.
But the take away from the white paper is yes, there's a .33 average difference in light transmission in water and air due to refraction..
so the conversion would apply to both meters.


yup. and most don't or wont do a Lux Par conversion on led...Yet

So you're saying I'm really 744 par at 2 inches? Now would that apply to the lux meter reading or just par?

 

[ksc]

The 32% only applies to the mq 500. I think the mq200 is only "off" 7% underwater. Make sure you keep the par sensor level, it's easy to get inaccurate higher readings angling the sensor towards the sweet spot.

 

[saltyfilmfolks]

So you're saying I'm really 744 par at 2 inches? Now would that apply to the lux meter reading or just par?

check out the white paper. the apogee is designed to meter light in the air. they found that there is a .33 difference in light in air and under water.
so they say ad .33% to your results. a lux meter would suffer similar air water transmission.
both are metering under water with a white ball.

 

[ksc]

So assuming the par meter is correct, the lux meter is only off by about 50%....

In the water:
2" - 23000 lux - 560 par (this would be 739)

739 x 50= 36 950

 

[gus6464]

So assuming the par meter is correct, the lux meter is only off by about 50%....

In the water:
2" - 23000 lux - 560 par (this would be 739)

739 x 50= 36 950

50% on lux side or par side?

Advanced aquarist pegs T5 conversion factor closer to 30 so the 739 and 23k lux puts it almost right there.

 

[ksc]

That's the problem when using an instrument to measure something it wasn't designed to measure. I imagine different lux meters would need different conversion numbers too. You use 30, I used 50. So it looks like 30 works for the Milwaukee MW 700 when measuring an ATI 8 bulb using these bulbs:
Blue plus
Coral plus
Attinic
Aqua blue special
Blue plus
Purple plus
Coral plus
Blue plus

 

[saltyfilmfolks]

So assuming the par meter is correct, the lux meter is only off by about 50%....

In the water:
2" - 23000 lux - 560 par (this would be 739)

739 x 50= 36 950

explain how you got these numbers again please?

where are you adding immersion, or are you?
are you adding it to both meters?

50% on lux side or par side?

Advanced aquarist pegs T5 conversion factor closer to 30 so the 739 and 23k lux puts it almost right there.

I believe several deeper blues were a slightly higher conversion.

 

[saltyfilmfolks]

I imagine different lux meters would need different conversion numbers too.

par meters too i would suppose. depending on sensor quality.