What's the deal with PAR vs. PUR? | Reef FAQs

randyBRS · Jul 10, 2019

It's Reef FAQ time!

Should you measure PAR or measure PUR? There's several camps out there that tell you either one of these are the most important approach to measuring your light's intensity.

Today, Ryan discusses which bit of advice to listen to.

raymanucy · Jul 12, 2019

Which is better to measuring your lighting for a mixed reef tank PAR VS LUX meters? I might be wrong but Milwaukee has a lux meter that I bought 4-5 yrs ago. I don’t know if BRS sells them only because I haven’t checked. Can you tell me what I need to ( as per numbers ) have with a lux meter for a reef tank. Also, can you give me a comparison chart for PAR VS LUX ?

vangvace · Jul 13, 2019

PAR over LUX. The conversion factor varies between the two based on light source. For led lighting, that means a conversion for each led type for the most accurate, or a rough conversion of LUX divided by somewhere between 50-60 = PAR... ish

https://www.advancedaquarist.com/2008/2/review

Hans-Werner · Jul 15, 2019

LUX is a measurand adjusted to the human visual perception. It nearly turns the PUR curve and weighting upside down (compare to coloured absorption curve above on right side). It is only a slight exaggeration to call LUX the "photosynthetic unusable radiation".