[tray262]

I wondering how long do T-5 bulbs last, how often will I have to change them out ? I'm just wondering becasue I've had mine for about 4 months now.

Thanks,

[charlie]

No personal experience with them myself, but if you do a little looking around here, I think you might be able to get an answer. I am thinking 6-8 months before they lose their juice, but I may be incorrect.

[Reefland]

I would replace all flourescent lighting at 12 months maximum. This includes VHO, PC and T-5.

[Samper]

I replace my T5's every 9 months.

[tike]

I just started using T-5 lighting and i have heard of people with sps dominant tanks in europe running their lights for almost 2 years before replacing them. I just switched in October so i'll keep all posted on my experience with them.

[Mr.Firemouth]

18 months is what most manufacturers recommend.

[Ninong]

Originally Posted by tike

I just started using T-5 lighting and i have heard of people with sps dominant tanks in europe running their lights for almost 2 years before replacing them.

This is a matter of personal choice. Some people may be willing to wait until their lamps have lost 40% of their intensity but others may prefer to replace their lamps after they have lost 25% of their intensity.

If you had a luxmeter (they're about $90), you could take measurements under your lamps (say at the water's surface) about a week after you fire them up and then take follow-up measurements once a month thereafter to chart their falloff in intensity.

With metal halides, there is also the problem of some of them degrading unevenly across the spectrum. In other words, they may shift to red faster than they drop in intensity. Some metal halide lamps need to be replaced every 6-9 months and others can go 18-20 months -- most need to be replaced every 12 months.

Whether you're running fluorescents or metal halides, just remember that if you wait to replace the lamps after they have dropped by 40% in intensity, the new lamps will be 166% stronger. If you replace the old lamps after they have dropped 25% in intensity, the new lamps will be 133% stronger. One thing you can do when running fluorescents is that you can swap out the lamps one at a time instead of all at once.