i just finished up two runs with a couple 1000 watt hortilux bulbs. i was wondering how long you guys are using yours for before you decide to replace them. these bulbs have never been on for more then 12 hours at a time. my two flower rooms are perpetual and they run 12 hours on/off until they are replaced. i figured i would just replace them after every three harvests. that would be 6-7 months of use running 12/12. do any of you replace them based off of light meter readings? i might buy a light meter and then see what the lumens read brand new and replace them after a certain percentage of lumen loss. appreciate the input.