At Growers House we wanted to know how well reflectors emit light in comparison to each other. So this is what we did: We chose three of the most popular large reflectors on the market, drew out a 5.5' x 5.5' square footprint, and collected Photosynthetically Active Radiation (PAR) readings from 13 points inside our footprint.
How did we run our test? - We ran it using a Sun System PAR meter. We used this meter instead of a luxmeter because measuring lux or lumens only measures the light visible to the human eye. Lumen measurements are used for HID bulbs when they were used as street lamps (their original use), to translate the brightness to the human eye, not necessarily the brightness in the spectrum that plants use to photosynthesize. The PAR meter measures the intensity of light within the spectrum 400 nanometers to 700 nanometers, which encompasses the wavelengths--both red and blue--that plants use to photosynthesize.
[caption id="attachment_119" align="alignnone" width="450"] PAR Spectrum with Nanometers for Photosynthesis[/caption]
The three reflectors we used for the test are:
1. Quantum Massive 8"
2. Sun System Magnum XXXL 8" (The Ocho)
3. Hydrofarm Raptor 8"
We hung each of these reflectors over our 5.5' x 5.5' area and took PAR readings at designated points. We measured each of these lights at three different heights: 24", 36", and 48." We used a 1000w Agrosun HPS bulb with 146,000 initial lumens. We used this bulb on a Quantum 1000w digital ballast. Before measuring each reflector, we let the bulb warm up for 30 minutes to reach its normal operating intensity.
Final Notes - We attached athe raw data collected to this test below, and although we have added some meaning to those numbers, we realize that much more can be done with them. If you feel so inclined, please make more meaning of the numbers below by whatever creative means you think up. The more knowledge we have for indoor growing, the better growers we'll all be.