whats with all this PAR all of a sudden?

nuro

nuro

Member
can someone please explain PAR to me, and why its suddenly being quoted as the new standard for lighting in a significatn amount of lighting threads. From my understanding of PAR froma quick google search it looks like it specifically in reference to the sepctrum and how that spectrum will affect clorophyll. why is this being touted as more important then watts per gallon? the basic WPG rules should still apply. as should the K ratign of a the bulbs(which in tunr should affect the spectrum).
I feel like we're overcomplicating things here with PAR all of a sudden.
 
J

jstdv8

Guest
Im new to this but it was my understanding that certain types of bulbs gave off more powerfull helpful light than others. I was told that t5's would give off more helpfull light for the same wattage than a compact flourecent.
I beleive (if this is true) that this is why people are straying from WPG, because it is not apples to apples accross the board from one lighting type to another. Where PAR is PAR. you measure it under the lamps and get a measurement, just like temperature.
Again, Im not an expert, but this is what I've come up with from reading
 
spanko

spanko

Active Member
PAR = Photosynthetically Active Radiation. A spectral band of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. If you think in terms of the zooxanthallae that are the symbiotic "photosynthetic organisms", read algae here, that are working with our coral we are trying to suppley the correct spectrums of light in the intesities required to grow this algae. In turn it will supply the needed glucose, glycerol, and amino acids, which are the products of photosynthesis so that the coral can grow.
High end explanation there but you get the point. Light in the correct range helps the algae to grow and that helps the coral to grow.
 
dean1956

dean1956

Member
One more thing for you to be convinced you don't have the right equipment so you will go out and buy the lastest.
 
scsinet

scsinet

Active Member
One reason for PAR is that new lighting technologies on the market changed the game. Watts per gallon was fine as long as everyone more-or-less understood how much light came out of an actual watt. Halides and fluorescent variants (NO, HO, VHO, T5, PC, etc) all were more or less of similar efficiency, so even though watt - as we look at it - is only a measure of power draw, it could be more or less correlated to a unit of light output. It's just like old-school incandescent lamps... we don't say "Bring me a 750 lumen bulb," we say "Bring me a 100w bulb," even though lumens is a measure of light output, not watts - but everyone pretty much understands how much light comes out of a 100w lamp vs. a 60w, etc.
Nowadays though, some lighting technologies (most namely LED), have rewritten the book, because if you put X watts of LED next to X watts of halide or fluorescent, the difference would be enormous because LEDs are so much more efficient at converting those watts into light output.
The industry has turned to reflector technology as a big differentiating factor in the performance of a lighting system. A system with a crap reflector but great lamps won't perform as well as one with great reflectors and no-so-great lamps. PAR can take these differences into account.
Also, PAR is a standardized unit of measure, which can be used to compare different makes/models of lamps. For example, watts per gallon might be fine to guestimate how many watts of halide, PC, or T5 light you need, but how do you compare different halide, T5, or PC lamps of the same wattage? You need a unit of measure that is useful to hobbyists that can be used to tell if you are getting a quality lamp and if you are getting what you should out of your lighting system. Hence... PAR.
Frankly however, when you are talking about Halide and fluorescent technology, watts-per-gallon is still a relevant figure when sizing fluorescent and halide based lighting systems. IMO only 10% of the folks out there really understand it. The other 90% have jumped on the bandwagon because on most message boards, if you even mention wpg, everyone laughs at you. The figure is more a fad than anything else. Yesterday, wpg. Today, PAR. Tomorrow, PPFD.
 
nuro

nuro

Member
excellent explination, ty. i wasnt really thinking in terms of LED's so i can see where that differenciation is needed now. I was just thinkign accross the board with florescent and halide bulbs which is why i didnt recognize the need to a new standard. thanks again for the explination... ill come back to it in 5 years when im readdy to jump to LEDs :)
 
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