PAR not the definitive measurement? PAR vs. PUR

[sphelps]

While the theory behind PUR is pretty sound the problem is it is still all theoretical and it's important you recognize that. Nailing down what spectrum all your corals benefit most from is virtually impossible as not only do different corals use different wavelengths based on depth and origin but they are also capable of adapting over time. PAR is still an accurate way of gauging usable light as it measures light within ALL usable wavelengths, to start nitpicking stating otherwise or more likely a way of justifying lower par values. Remember the bulbs and LEDs we use are already focused in on what corals tend to use more in general so realistically PUR theory has already been accounted for before we even break out PAR meters. Also consider most hobbyists agree from experience a 10K bulb promotes better growth than a 20K which supports PAR yet goes against PUR theory.