bang guy
Moderator
Lux meters are pretty cheap. They are not accurate in how much actual light a bulb produces but they are extremely accurate in measuring how much bulb output changes over time. After using a bulb for a week or so (break in period) measure the lumens. You probably don't need to replace until lumen output drops 25%. You can pick whatever number you want though.
Also, with your variable output you could continue to slowly ramp up the bulb output as the lumens begin to decline.
I'd also suggest to never change out all of your bulbs at the same time.
Also, with your variable output you could continue to slowly ramp up the bulb output as the lumens begin to decline.
I'd also suggest to never change out all of your bulbs at the same time.