Lumens and PAR

[sen5241b]

I've heard PAR is a better measure of light than lumens but I've found it very difficult to find info on PAR for a given light fixture.

2 questions:

Is there a way to convert lumens to PAR?

How many lumens do 'high' light corals and clams need?

 

[ccCapt]

Is there a way to convert lumens to PAR?

No. It's like converting an apple to an orange. Lumen is a measure of precieved power of light and PAR is Photosynthetically Active Radiation. A lumen can have 0 PAR depending on the spectrum of light it emits.
A better measue is PPFD - Photosynthetic Photon Flux Density, which is the amount of photosynthetic available light emitted from a bulb in a defined area. Keep in mind photosynthesis is very active in a reef tank, so we want light that is available to use in that process.
There is no set rule that says x coral needs more light than y coral, besides the basic low light for soft coral, med light for LPS and high light for SPS.
Here's some good reading.
Photosynthesis and Photoadaptation by Sanjay Joshi

 

[lightcs4]

+1 Capt.