With fluorescent bulbs it is watts which are used to compare for light power. Light temperature is measured in Kevins and that is the large number you see on some better packages with the K stuck on the end. Kevins are as important in reef keeping as any other light property. PAR is a measurement taken with a special probe that is intended to measure the amount of light which is most effective for growing plants. Lumens are another measurement of light value and are most useful for photographic needs. We have a fair grip on which Kevins are good for what aspects of reef keeping, power in its various measurement readings is highly confused and opinionated, and there are even additional types of measurements for lighting. All of these measure different things and NONE of them really tell the full story of effective light projection into a reef tank. We just have to use what we have to do the best we can when comparing notes from one successful reef tank to others. I have a PAR probe and it is useful but is a disappointment in that it is not nearly as useful as I expected. We still do not know all the aspects of light. We still do not know all the aspects that various plants and corals are "looking" for. We do have some reasonable data and as well some knowledge of a few things they are "looking" for. As a result of all this missing information and on going research we have numerous opinions. These opinions are based on personal and exchanged successes and failures with what we do know about light. Now when you toss in LEDs and their constantly advancing technology you really shuffle the deck and open up a whole new can of worms, we know they are effecting corals in positive ways and sometimes others not so much. With LEDs we still have more questions than answers, we do know they affect life forms differently and we are trying to figure it out. We do know we are making frequent advances with LEDs and some lighting units are giving amazing coral growths and color achievements. However, we have just begun to understand LED effects for good and bad. IMO LEDs will be the future of lighting, period, but we are still reaching for the apex of technology with them. One thing we can count on is that their are plenty of companies investing plenty of money to research and develop the race towards being the first to patent the future with LEDs. So, it will happen.
Digest all that, yet?
So, yes, you can get some good advice but you will have to do some fine tuning on your own part as every reef tank is different. I hope you are driven by challenges, if so, reefing is your hobby.
