When to trash the bulbs..?

[bubbels]

hey i use a son-t pia green power 600w and i dont know how old they are. starting 12/12 now so i doesent want to find out at the end that the bulbs was bad and i dont want to buy new if i dont hawe to. so what can i do to measure my ligths.? will a lux meter do the job.?

thanks for any replye

[scrumby]

At the end what you see is what you smoke.