Correcting For Spectral Errors of Common Electric Lights (Aquarium MQ-200)
The reef tank lighting market has recently grown exponentially with hundreds of lighting options now available, due to the increased popularity of reefkeeping. Unfortunately, all types of electric lights have a unique spectrum, therefore, they yield a unique set of spectral errors when measured by any commercially available PAR meter. In response to emerging electric lighting technologies, Apogee has done extensive research to help customers make accurate PAR readings. Spectral errors for different commercially available lights were determined via the method proposed by Federer and Tanner (1966). These results are found in the table below.
The spectral errors of common lights such as CWF, CF, MH, and HPS are fairly straight forward. To make high precision PAR reading for these types of lights, simply recalculate the PAR reading given by the meter with the corresponding percent error from the table below to yield a more precise PAR measurement. LEDs present a challenge when attempting to make accurate PAR measurements. With commercially available PAR meters, certain colors of LED tend to read high, while others read low. When used properly, the MQ-200 offers a very reliable and economical solution for precisely measuring the PAR output of LEDs. To achieve the highest level of accuracy, simply recalculate the PAR reading given by the meter with the corresponding spectral error percentage from the table below.
Federer, C.A. and C.B. Tanner, 1966. Sensors for measuring light available for photosynthesis. Ecology 47:654-657.
Apogee PAR Sensors Spectral Errors Under Electric Lights
All Quantum/ PAR sensors on the market experience a certain level of error under different electric light sources. The following data can be used to adjust the PAR readings of Apogee Original Quantum sensors to achieve highly accurate readings. Please note these errors apply only to Original quantum sensors that are pre-calibrated for electric lights and to the Original Quantum Meter when it is set to "electric light" mode.
NOTE: The spectral errors below are for original quantum sensors.
| LED Type | Error [%] for Apogee Quantum Sensor |
| Cool White | -4.2 |
| Neutral White | -6.1 |
| Warm White | -9.9 |
| Blue (448 nm) | -10.7 |
| Green (524 nm) | 5.8 |
| Red (635 nm) | 4.7 |
| Red, Blue | 2.7 |
| Red, Green, Blue | 3.5 |
| Other Electric Lights | Error [%] for Apogee Quantum Sensor |
| T5 Cool White Fluorescent | 0.0 |
| T8 Cool White Fluorescent | -0.3 |
| T12 Cool White Fluorescent | -1.2 |
| Compact Fluorescent | -0.2 |
| Metal Halide | -3.9 |
| High Pressure Sodium | 0.8 |