Hey, how often do you all replace your bulbs? I know these last a lot longer than HPS or regular MH bulbs, but I think the info I had was not quite right. I had read that they maintained 85% PPF at 20,000 hours. I just replaced mine (for the first time) at about 9,200 hours, and it was a HUGE difference.
I use a cheap light meter to give me an idea of light intensities, then use conversion values I found on the web to convert that into PPFD values. I know it's not very accurate, but it gives me a ballpark figure I can work with.
When I replaced my bulb at 9,200 hours my measurement under the light went from 600 PPFD to 1000 PPFD. That is a HUGE jump.
Any input?