Purchase Aquarium LED Lights
Gregg
It is important to note that an LED (or any light) can test well for PAR using a PAR meter, but still have poor “Useful Light Energy” (PUR)!!
If using Apogee MQ-200 PAR Meter or similar to test PAR value you can get similar µMol•m²•sec numbers from one LED to another.
A PAR meter can sense and report light (‘photons’ or ‘quanta’) that are
responsible for promoting photosynthesis which are the wavelengths that
are between 400nm and 700nm.
However, if one of these lights produces energy that peaks at 450nm,
or the blue spectrum; while another light peaks at 520nm, or the yellow
spectrum; your reading comparison is not all that accurate since the PAR
Meter reading will be similar, yet the light producing the exacting
450nm bandwidth is clearly the better light to use, which is where a PAR meter is often over rated!.
For zooxanthellae in your coral’s tissue, the light peaking at 450nm
will have greater PUR than the light that peaks at 520nm, although the
PAR mmol readings are the same.
Similar can be stated about relying on PAR only for a planted freshwater aquarium, especially since many fluorescent lights can be heavy on the yellow/green spectrums which a PAR meter does not differentiate. This is also a problem with many LEDs that rely on “cool white” emitters, which unfortunately many of even the pricey LED fixtures utilize these less than desirable emitters!
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