The Planted Tank Forum - View Single Post - Lighting an Aquarium with PAR instead of Watts
View Single Post
Old 07-22-2012, 04:54 AM   #14
Hoppy
Planted Tank Guru
 
Hoppy's Avatar
 
PTrader: (75/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 18,975
Default

It is also noted by some people who have measured PAR for their light, that bulbs with different color temperatures, 6500K and 10000K for example, produce different PAR. For now I think it is hard enough to characterize what a given light fixture produces in PAR vs distance, that the finer points, like color temperature, will just have to wait a few years. The difference in PAR from a 10000K and a 6500K bulb is probably within the uncertainty range for most lights. And, all of this data is from lights operated out in the air, not in a water filled tank, where the difference is also probably within the uncertainty range for most lights.

Tonight I was measuring PAR from a screw-in CFL bulb in a dome type reflector. I noticed that on turning on the light the PAR slowly increased for a minute or two, then even more slowly dropped part of the way back. It was an old bulb, so this may be a problem with the bulb's built in ballast. Imagine the error this could introduce if you didn't allow for it.
__________________
Hoppy
Hoppy is offline   Reply With Quote