Using a lux meter as a PAR Meter - The Planted Tank Forum
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post #1 of 4 (permalink) Old 09-27-2012, 09:46 PM Thread Starter
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Using a lux meter as a PAR Meter

If you have a Mastech lux meter, probably purchased from Amazon, you can do a very simple modification of the sensor to make it read PAR units directly - no need to divide the reading by 76. This involves just removing two screws on the back of the sensor, laying a stack of 6 half inch square filters on top of the sensing surface, using a couple of small pieces of Scotch tape to hold the stack of filters in place, putting the sensor back together - 2 screws, and you are done.

You can get the filter material free from Rosco filter retailers, but I have their free filter samples, and have lots of extra filter material, so I will mail you a stack of the right filters at no cost. Just PM me if you want it. Obviously this would be limited by how much filter material I have, but it is at least enough for a dozen lux meters.

One minor problem: those meters automatically calibrate themselves when there is zero lux. When you do this mod it may take several times turning on the meter with the sensor cover in place before it will read correctly. When I have had this problem the meter reads a constantly changing 1500+ lux instead of zero, but eventually the electronics recognizes what happened and it reads zero correctly.

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post #2 of 4 (permalink) Old 09-27-2012, 10:25 PM
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Wow, So a Par meter for $30 .. this is amazing. I am guessing you cant take readings underwater ?.
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post #3 of 4 (permalink) Old 09-27-2012, 10:33 PM
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thanks hoppy for all your work ro find the right recipe i did find the meter at the amazon and will order it i hope on the first.
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post #4 of 4 (permalink) Old 09-28-2012, 12:23 AM Thread Starter
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Those Lux Meters do not have waterproof sensors, so they are only good for checking how much light your light fixture produces. You can't stick the sensor in the water to measure PAR in the tank. But, you can make your own waterproof sensor cheaply and without too much difficulty


Last edited by Hoppy; 09-28-2012 at 01:40 AM. Reason: add more info
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