ppurcell
08/15/2007, 05:35 PM
I've read that MH Bulbs are good for roughly a year. And I've seen some posts and statements that say that for some bulbs the PAR will drop significantly after six to nine months. What I have not seen are graphs that show the drop-off over time measured in hours of operation.
So, if you assume a 12 hour photoperiod for a given bulb this would result in 4,380 hours of annual operation. If the bulb loses 30% (assuming 30% is acceptable) of it's PAR after nine months, then the bulb should be replaced after 3,285 hours of operation.
Is this sort of information available anywhere? Does it vary with every bulb/ballast combination or is there a general rule you can apply? Do I need to go spend a few hundred bucks on a PAR meter or just assume the bulb is spent after running it for 6.5 hours a day for 9 months?
So, if you assume a 12 hour photoperiod for a given bulb this would result in 4,380 hours of annual operation. If the bulb loses 30% (assuming 30% is acceptable) of it's PAR after nine months, then the bulb should be replaced after 3,285 hours of operation.
Is this sort of information available anywhere? Does it vary with every bulb/ballast combination or is there a general rule you can apply? Do I need to go spend a few hundred bucks on a PAR meter or just assume the bulb is spent after running it for 6.5 hours a day for 9 months?