New Light Bulb?

how do you know when its time to get a new light bulb? (for 600 watt) do the bulbs burn out or does the quality noticeably diminish? Thanks!!!

6 months replacement is the general rule but many growers run them for a year or more . Simply looking at a bulb will not always tell its burn time and lumen loss , hence the use of light meters or a simple schedule for replacement . Although many growers push the thresh of a yearly replacement it is up to you , some people are happy and content with bulbs that are several years old .

thanks!! can you guess when its time to replace the bulb with the way light affects the plants? ie. more sparse growth or over all less growth? or is a year a rule of (green) thumb?

You'll need a light meter to know for sure, if your worried about output buy one at a home depot or so. It will be cheaper in the long run rather then guessing. And no you won't be able to tell by eye.

thanks!! (sorry for the delay in responding)

damn 6 months really I thought it was a year!