What is PPFD and PBFD and How Are They Measured?

Photosynthetic Photon Flux Density (PPFD) is the metric used to measure PAR over a square meter. It is a total count of light energy (in photons) from 400nm to 700nm that reaches a particular point on a plane.  Photobiological Photon Flux Density (PBFD) is the metric used to measure PBAR over a square meter. It…

LED vs. HID Technology

There are many differences in LED and HID technology for plant growth. Arguably, the largest difference facing growers is up-front cost because LED systems are much more expensive to purchase than HID systems. On the contrary, maintenance of an LED system is minimal as you do not need to regularly change out lamps to maintain…

What is Efficacy?

Efficacy Photosynthetic Photon Efficacy is the amount of light emitted for a given amount of power used. In horticulture, efficacy is measured taking the PPF of a light source’s output divided by the input power (see equation below). The higher this number, the more efficient the fixture is producing light, however it does not provide…

LED System Anatomy

LED – the light-emitting portion of the LED system. There are three main diode types: mid-power, hi-power and chip-on-board (COB). All three can be found in LED grow light systems, though mid-power is the most common due to their low cost and high efficacy. Driver – converts the AC power from a wall plug to…

HID System Anatomy

1. HID Lamp – the light source. Also referred to as a grow light or bulb. 2. Ballast – an electrical device that supplies power to the HID lamps. The ballast takes the available voltage from your electrical outlet and ramps it up to provide a high-voltage pulse to start the lamp. It then regulates…

Fixture Uniformity and How to Measure It

Uniformity Uniformity refers to the fixture’s ability to provide even light distribution over your plant canopy. Poorly designed reflectors can create patterns of light with hot spots where more light is directed. Uniform light distribution provides consistent light levels to plants across the canopy. The fixture comparison image below shows how two different fixtures produce…