Testing LED intensity output?? PAR or LUX meter
 

I want to test what the output is on my diy LED's are but don't know what meter I need, a lux or par meter. I can get a lux meter from J&L for a lot cheaper then the par meter from Apogee.

So if there are any experts out there that can explain the difference in layman's terms so I can understand better it would be helpful.

light
 

i use a par meter.after taxes they are $500.too bad your in alberta,i could have lent you mine.when measuring led output add 10-25% to the reading

No personal experience here, but from what I've seen on various threads about the subject of measuring LED photons, it's quite tricky. Apparently most of the metering equipment out there & in common use for our hobby is geared towards older technology, MH, flourescent etc. Certain spectra that the LEDs put out (blue, UV etc.) can skew results, especially when using a PAR meter.

lux meter tells you nothing, PAR meter will tell you the numbers you want. you can get a PAR sensor you use with your multi meter for around 100 bucks from apogee if they are still selling them.

Steve

Thanks for the input guys, I think I will have to just pull the trigger and order the Apogee par meter as it has the water proof sensor as well as a compensation guild to adjust reading for LED's.

As Stircrazy said, apogee sells just the sensor which you hook up to a multimeter. One that reads at least 0-500 mV
Here is the manual:
http://www.apogeeinstruments.com/con..._300manual.pdf

And a good read
http://www.advancedaquarist.com/2013/2/equipment

Those are great links, thanks for sharing. I have an old light meter from the 'film' camera days and have often wondered if I could somehow use it to measure the light output of my fixture(s). Searches for conversion of LUX to PAR a couple of years ago didn't yield much in the way of useful info. The tables on the Apogee site & in the Advanced Aquarist articles appear to have what I may need without having to purchase a sensor. I do have a multi-meter at home, as I'm sure many others have as well, so the Apogee option of simply buying the sensor is awful tempting.

In the end though, it does still appear to be a tricky proposition to get useful data trying to measure the light output a LED fixture, particularly the UV, Blue & Red spectra. One of the best ways to tell if you have the appropriate spectrum & enough intensity with your LED fixture still appears to be personal experience & a few months of actually running a fixture above your tank. But that has it's own risks in that you can easily burn certain coral trying to eyeball light intensity instead of measuring it. Most LED lighting manufacturers have now done the research & are providing fixtures with intensity & spectra that work pretty well depending on what you're keeping in the tank. For us DIY folks, it's a bit of a gamble & takes some research to get the LED combination right. I reckon a PAR meter or sensor is probably not a bad investment. Might have to jump on the bandwagon after all & get one of these, depending on price & availability.

while the conversion is there it is still not proper as it assumes all the light the lux meter is reading is in the PAR range. so it will only work if the lights you are measuring put out nothing but light in that specific range, other wise you will get an artificialy high par number after the conversion.

Steve