Quote:
Originally Posted by
tlsohio http:///forum/thread/381345/watts-lumins-foot-candles-par-this-is-the-question#post_3321052
Ok first, Just to be clear, I've never heard of PAR (parabolic aluminized reflector) as a measure of light and that is what we are talking about here..right??
And I agree, that especially today with the new technology in lighting that the watts ratio is outdated, but how would you describe in simple terms to new hobbyists, how to measure light per gallon needs, when they are trying to buy a new fixture? There has to be a calculation that helps the reef hobbyist do this. No matter how outdated watts may be, bulbs are still sold on a watt basis. Is there a chart somewhere that helps hobbyists make this conversion, with all the light sources available there has to be information somewhere, that gives the PAR that each light type produces at different depths?? Doesn't there??
Quote - "No doubt though, corals could care less about lux or the luminous output of lighting when all they are interested in is the usable radiation that is being created by the source."
With that said, I'm looking for information that helps us to do a PAR calculation on lighting needs based on volume of gallons. Or is a PAR calculation only for individual coral needs at a certain depths???
Yeah I think there are alot of variables here that need to be considered on an individual basis before one could assume that a one size fits all solution would work well for everybody. Take a 54w T5 bulb for instance. There are different manufactures of bulbs, ballast, reflectors...etc. Depending on the type of ballast that you are driving that bulb with can change it's intensity greatly. Just like reflectors. Using a cheap reflector or no reflector isn't going to give you the same PAR (photosynthetically active radiation) measurements as a well designed PAR (parabolic aluminized reflector) will. You can also throw a larger ballast on a T5 and overdrive the bulb thus increasing it's output as well. Some bulbs even have built in reflectors which give them a better focused output than ones without. Depth of tank, spread, space between the fixture and top of the tank, power...etc. All of these things come into play and have an effect on the measurements of PAR that you'll see.
As Spankos link and Bang Guy have suggested... figuring out the actual amount of usable radiation that would be required by an individual piece of coral would be the holy grail. But it would be impossible to figure out a one size fits all rule, IMO. In general, there have been enough tests done on all of the different types of lighting to give anyone a good enough idea of what will be required for what they plan to keep if they're are willing to search for it and come to their own conclusion on what will work best with their particular set ups.
In regards to your last question...calculating PAR on a per gallon basis would never work IMO since these measurements will change depending on the depth of which is being measured. I think it would be better for someone to measure the PAR values of their particular tank and then plan accordingly in regards to the placement of corals within their tank.
