Syntax1235
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Can you elaborate on this comment please?
Par to lux conversion - real world T5 numbers
- Thread starter Scott.h
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Can you elaborate on this comment please?
The fixture only has two small emitters. When mounted 12in above the 48in wide tank the the light intensity dropped off very very little from eggs to edge.
It was 35000 lux btw.
Acro maniac
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Below the water or by the way?
above at the surface. All light falls off evenly and at a given rate. Optics in some leds confuse this esp if theyre mounted too close. But if the fowls of light is even at the top it will fall off evenly all the way down. If one were to measure par in an empty tank we'd see this, its usually in the maufacturer specs as a 3d map in fact.
Many note a change in the field at the same level/distance from a light. this is due to the sensor not seeing the entire source(light). Like metering on the extreme left or right or the presence of a different color. White rock for example and white sand. White bounces light and adds to the intensity.
Acro maniac
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Ok i got my lux meter and also a spectrometer.
The lux reading divided by 60 for led .
Is 60 a comstant regaurdless of how many leds and spectrum ?
Also the add 30% for underwatrr readings is 30% a constant? Or does that change with each meter?
The lux reading divided by 60 for led .
Is 60 a comstant regaurdless of how many leds and spectrum ?
Also the add 30% for underwatrr readings is 30% a constant? Or does that change with each meter?
No. I just average 60 as the estimate.
Acro maniac
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What is the 60 average based on? Is there a calculation for output / amount/ coverage for leds?
Also what about the 30% added for underwater readings?
lux par conversion constant. it from a LOT of observation and conversation with users par lux data. see the D Riddle for an in depth explanation. 30% is the calibrated number the new apogee uses on one specific meter. this number is not used on any other meter. browse back through the thread.
Acro maniac
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Thanks ive been through this and othrt threads a few times. Just tring to put all the pieces together.
No sweat. It does get confusing.
OP
OP
Scott.h
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I was figuring divided by 57 with my own tinkering and figuring. I also felt the blue end was a little light with the led lux reading. So our figuring separate from eachother was pretty close.
Khalifa Alhaddad
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Thanks Man
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.
you make things easy for LUX users
OP
OP
Scott.h
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No problem. Don't get too hung up on numbers. The more junk I buy the more I realize paying attention to the corals makes the most difference. That fixture is currently running 50% with sps at middle doing fine.
