As I learn more about aquarium lighting (thanks in good part to you kind people here) my questions become more basic and, possibly, dumber.
I have learned that both PAR and Lux refer to the amount of light energy (photons) that strike a surface a distance from a light source.
Both refer to the energy that is produced by light in the 400 to 700 nanometer range, that part of the spectrum that is visible to people and usable to plants.
A key point is that neither distinguishes between the energy that is produced in the red and blue parts of the spectrum, the part of the spectrum that is useful to most aquatic plants, and that produced from other parts of the spectrum. PUR refers to the blue and red parts of the spectrum.
Both PAR meters and Lux meters measure all of the energy that comes from the 400 to 700 nm range of the spectrum. It is possible that each could give show a high, supposedly plant-friendly reading if enough energy was produced in the yellow and green parts of the spectrum, which is not as valuable to plants.
A PUR meter would be more useful in determining the plant friendliness of a light source, but they are very expensive.
The main reason for using PAR and par meters instead of
Lux and Lux meters is that the former is the measurement of choice in the scientific community.
Please tell me if any of the above is incorrect or arguable.
Thanks.
Bill
I have learned that both PAR and Lux refer to the amount of light energy (photons) that strike a surface a distance from a light source.
Both refer to the energy that is produced by light in the 400 to 700 nanometer range, that part of the spectrum that is visible to people and usable to plants.
A key point is that neither distinguishes between the energy that is produced in the red and blue parts of the spectrum, the part of the spectrum that is useful to most aquatic plants, and that produced from other parts of the spectrum. PUR refers to the blue and red parts of the spectrum.
Both PAR meters and Lux meters measure all of the energy that comes from the 400 to 700 nm range of the spectrum. It is possible that each could give show a high, supposedly plant-friendly reading if enough energy was produced in the yellow and green parts of the spectrum, which is not as valuable to plants.
A PUR meter would be more useful in determining the plant friendliness of a light source, but they are very expensive.
The main reason for using PAR and par meters instead of
Lux and Lux meters is that the former is the measurement of choice in the scientific community.
Please tell me if any of the above is incorrect or arguable.
Thanks.
Bill