LUX meters measure the quantity of "visual" light striking a surface. PAR meters measure the quantity of "grow" light, the light energy that plants need to proliferate.
HYDROFARM LIGHT METER (LUX) This light meter has settings for sunlight, HID light & fluorescent lighting. It comes with an informative booklet on plants & their lighting requirements. This is the best way to determine when to replace bulbs.
QUANTUM METER (PPF) Measure the energy that plants really need. Photosynthesis & plant growth depend on the energy in radiation but only specific types of radiation cause photosynthesis. We have known since Einstein that one photon excites one electron (the Stark-Einstein law), which starts photosynthesis. A meter that counted the photons in radiation would more accurately predict photosynthesis than any footcandle light meter. This system is called the Photosynthetic Photon Flux (PPF). This type of meter, up to now, was very expensive & only used by large commercial growers or research scientists. But with this price breakthrough, you too, can make accurate measurements for optimum plant growth.
DIGITAL LIGHT METER Get accurate light reading with this digital light meter. Handy remote probe reads up to 5000 footcandles in 3 lighting scales. Includes battery, instructions & carrying case.