When should I replace bub?

When should I replace my 400w HPS bulb?

the normal life of a HPS bulb is about 20,000 hours and about half that for a MH bulb. but that doesnt mean that the bulb is good for 20,000 hours, it just means it will last that long. i replace my bulbs after every harvest so that i get the best possible harvest everytime..

Most people replace there bulbs at least once a year.But if you have the money every grow.Good Luck & Stay Safe!!

Thanks. I'll replace it.