Will a 2 year old 600w HPS still produce adequate light?

Hi everyone, was just wondering about how long an HPS lives before it starts putting out shitty weak light? Basically I bought a 600w Philips SON-T HPS with digital ballast second hand, I checked on the bulb and it says it was made in late 2010, assuming then that it has two years of useage (I know it will probs be a lot less because of 12/12 and that) should it still throw out plenty of useable light? Its just i had a 400w HPS before and its been a few years but i remember it maybe being brighter? I could have just remembered completely wrong but im not sure. I mean its damn bright and all, I just kinda expected it to be a bit more brighterer. er. I have a GHS trainwreck and some tomatoes and shit under it, obviously the bud is my priority though. Soz if that was a bit of an essay im a high wasteman.

hi ........eh no i would recommend to change the bulb after every 2 grows so dats after 6-7 months of contiune use ........ some will say less or longer ....... now you dont have to replace the ballast ... just da bulb and der only like 25 usd for a 400w any way so dont be leaving it for 2 years just sell a 1/8 oz and get a new bulb , and sorry yes the bulb does lose light after every grow drops buy about 4600 lumens

ah shit that's quite a lot. I think it seems a bit less hot as well though, how far away would you normally put a 600, its not air cooled but the box is like 26C cos I have a good extractor. I have mine like just under a foot away from the top and its not too hot there at all. Just wondering if that was a thing cos the lumens decrease exponentially over distance i think so if I can put it closer will that make up for the less lumens?

A foot is very close for an HPS 600. At least 18 inches from the very tops is my advice.

To estimate where your personal break-even is for cost v. output, here's a useful chart. One year is 8760 hours ... cn

Ah thanks thats a useful chart. I guess i'll finish the grow i've got then change the bulb... I thought that a foot was very close but like I said its really not to warm when I put my hand under the tops