View Full Version : Cheap(er) PAR Meter

11-04-2012, 03:09 PM
A PAR meter can be a valuable tool for many of us but even the most economical meter is $379. This cost can be hard to justify. As it turns out you can buy the sensor separately from Apogee and wire it to a standard multimeter.

Apogee SQ-120: Electric Calibration Quantum Sensor (http://www.apogeeinstruments.com/electric-calibration-quantum-sensor-sq-120/) $139

Commercial Electric Digital Multimeter (http://www.homedepot.com/buy/commercial-electric-digital-multimeter-mas830b.html#.UJa66cWulDA) $19.99

To connect the sensor you simply cut the leads to the multimeter and connect red to red and black to black. I soldered them but wire nuts would work just as well. The clear wire coming from the sensor is a signal wire and is not needed. The sensor is self-powered and sends its signal in millivolts. Each millivolt is equal to 5 PAR. You simply multiply the multimeter's reading by 5 to get the PAR value. I zip-tied the sensor to an extendable scraper from Petco to make measuring easier.

The meter claims an accuracy of .5% of the reading +/- 3 digits so for our purposes it is more than accurate enough. You do lose some of the data logging features of the Apogee meter but I'd personally rather save $220. Just thought I'd share.

11-04-2012, 04:58 PM
Thanks for sharing. Is the sensor saltwater poof? They just say weather proof.

11-04-2012, 05:03 PM
Yes it's completely submersible and saltwater safe.

11-04-2012, 10:54 PM
Excellent! I guess, I have to support the economy. :)