no guesswork needed with a par meter aye?
I accept some degradation before discarding, generally every 1.5 yrs. I dont know how to change with every cycle, as my lights are on non stop daily in a perpetual continuing harvest, with plants of all different ages in the flowering room full time.
my last t5 bulb change was recent but was years before that. they were degraded but I didnt care in veg.
hps;
But this Ushio has been burning for three with very little loss over time. Ima sticking with the Ushio for now.
I absolutely loved the badass bulbs, best performance ever, but she degrades quickly. Digilux was super fine to grow with, and little degradation, but my gen ready ballasts dont play nice with them, so I scrapped the digilux.
a meter is 30 bucks, lasts forever and will keep good bulbs from seeing the trash bin prematurely.