changing out T5 bulbs

[bee505]

I am running 6 t5 bulbs t5 fixture. Is there a rule of thumb for changing out t5 bulbs? Is it 6 months, 9 months, or 1 year. I look at my tank daily and I can't tell if I need to switch out the bulbs. I don't have a par meter.

 

[JAR]

How many hours a day do you run them?

 

[bee505]

I run them 8 hours a day.

 

[rygh]

Not really sure there is a rule of thumb. Probably depends a lot on type of bulb + ballast.
Bulbs tend to get discolored about the time they need replacing, but not a very accurate way to tell.
I guess I replace Actinics about 9 months, and white about 12 months.
That uncertainty is another reason I am going to all-LED soon.

 

[Gonzo]

I've read (from that Grimmreeper guy over on RC) that standard 8 hour usage of T5 bulbs will require replacement every 12 months. I don't see the harm in 9 months, but it probably comes down to your budget if you want to switch out every 9 months.