Active Eye Analog Light Meter is an easy to use, and reliable. The light meter will allow you to ensure that your plants are receiving the correct amount of light and will help you know when its time to replace your lamps.
It needs no batteries and will never require calibrating. Has three settings: X1 = low light or shade loving plants/fluorescent lighting systems, X10 = general sunlight and X100 = light loving plants/HID lighting systems. If the needle goes off the scale then turn up the setting higher.
Comes with 2 year warranty.
Light Requirements of "High Energy" Plants
1000 - 5000 lux Min. necessary for life
10000 - 15000 lux Min. necessary for consistent but sparse growth
20000 - 25000 lux Min. necessary for robust growth
25000 - 30000 lux Max. Efficiency for Sub Tropical varieties
25000 - 50000 lux Max. Efficiency for Equatorial varieties
Plants that get less than 30000 lux they will still grow vegetatively but slower. And they will flower less, if at all. Its best to keep the lux between 30,000-50,000 thoughout the plants lifecycle.