Which Light Source to Choose

Selecting the right light source setting is crucial for accurate PAR measurement

In order to measure PAR/PPFD accurately, it is required to select the correct light source setting based on the type of light you’re about to measure. This guide describes how to select the correct light source setting.

LED Grow Lights

If your LED grow light contains blue and red LED chips and thus looks purple, use the LED red / blue setting.

If your light is mostly blue use the LED blue / white setting.

For all other types of LEDs you should choose LED full spectrum. LED lights that have a color temperature rating ranging from 2000 K up to 7500 K are considered full spectrum. Your lamp might include some pure red (e.g. 660 nm), pure blue, ultra-violet (UV) and infra-red (IR) chips as well, nevertheless full spectrum light will appear white or yellow-ish.

HID Light Bulbs (HPS, MH)

If you’re using High Intensity Discharge (HID) lamps like High Pressure Sodium (HPS) light bulbs, make sure to use the Standard or Double-Ended setting based on the connector type. The Metal Halide (MH) Standard setting should be used for any MH light bulb independent of the connector type.

Ceramic Metal Halide (CMH) Light Bulbs

When using Ceramic Discharge Metal-Halide (CDM) or Ceramic Metal Halide (CMH) light bulbs, select the correct light temperature based on the information on your bulb’s packaging. CMH lamps are sometimes referred to as red / warm, which requires the CMH 3000K setting, or blue / cold which requires the CMH 4200K setting. Purpose-built CMH lamps for agriculture require the CMH Agro light setting. All of this information can usually be found on the packaging.

Fluorescent (FL) and Compact Fluorescent Lights (CFL)

If you’re using Fluorescent (FL) lighting or Compact Fluorescent Lamps (CFL) make sure to select the correct light temperature based on the information on your light’s packaging. If there is no exact match on light temperature, choose the setting that comes as close as possible to the indicated number.

Beware that your light may look like a fluorescent tube or CFL but uses LEDs to actually produce the light. If that is the case, please refer to the LED Grow Lights section for the right setting.

Natural Daylight / Sunlight

Choose the sun as a light source if you’re measuring natural daylight. It doesn’t matter if you’re indoors, outdoors or in a greenhouse. Please consider that window glass will, depending on its composition, block some sunlight. Thus, you will get different readings inside or outside of your greenhouse.

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Measuring Different Light Sources

If you use different light sources for your grow (e.g. LED Red / Blue and LED Full Spectrum), you must measure them individually. To do so, turn off all lights and measure each light source individually using the correct setting. Then add all the individual measurements to get the sum total measurement value.

Didn’t Find What You’re Looking For?

If you did not find the correct light setting for your grow light or are still unsure which light to choose, please contact our support.

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