PAR is micromoles/m^2/second so to convert seconds to liters is not possible. However, in my previous posts I realize that I did mix up the seconds with L... It is a bit late to change that now though lol But on a side bar just to contribute to the general knowledge of this post, I have discovered more on the needs of corals after researching LEDs and would like to share why PAR is not always a good way to measure. From halides which are full spectrum PAR is a great representation of good or bad light sources as all spectrums are coming from one source and are pretty uniformly distributed. Lets use a PAR of 250 for example, pretty decent number and is a mix of ALL wavelengths (no matter how intense they are) averaged out into one simple number. Now with the typical LED fixture you are looking at white and blue diodes. So you have a strong concentration in the 450nm range and then a mix of smaller very precise peaks between the 450nm and 600nm range to make the white. You put a PAR meter under this light you are still going to get a pretty high PAR value, lets say 300. But unfortunately, this value may be higher than a halide at similar depth but it does not tell us anything about the quality of this light source. In reality, the intensity is higher but the source is lacking critical spectrums that corals are used to thriving under (420nm, 650nm to 700nm, and all the ones in between the LED peaks). As a drastic example, one could take solely red LEDs and produce a PAR value of 400... But i can guarantee that your corals will be dead within a few weeks. To recap: PAR measures the quantity of light within the visible range, no the quality. By quality I mean a broad spread of spectrum throughout the range to satisfy whatever need the photosystems of each individual coral may have.