How long do T5HO bulbs last until they need to be replaced?

[londonloco]

I've googled this, and there is no definitive answer I can find. Reefing sites state 18 months, planted sites (both water and soil) from 5 - 7 years to never. I've also read some manufacturers say life of bulb is 20K hours which lit at 10 hours a day is over 5 years. Anyone here have the answer? Thanks!

[krisw]

I've always heard that T5's last 18-24 months. 5-7 years would be fantastic if true! I think it's a case of keep an eye on your tank. If your tank provides great growth for a year and a half, and then you notice that nothing else has changed, but things just aren't growing that well, and/or algae is becoming a problem, it's a good chance that you'll want to switch out the bulbs.

[londonloco]

I've always heard that T5's last 18-24 months. 5-7 years would be fantastic if true! I think it's a case of keep an eye on your tank. If your tank provides great growth for a year and a half, and then you notice that nothing else has changed, but things just aren't growing that well, and/or algae is becoming a problem, it's a good chance that you'll want to switch out the bulbs.

Why I'm trying to figure out if anyone has a definitive answer...I don't want not growing well or algae in my tanks...I know, wishful thinking. Thanks Kris!

[krisw]

I think it can vary upon a number of conditions, largely the temperature that the bulbs run at. Not all T5 fixtures are created the same, some have fans, some have splash guards, some sit directly on the glass, some use legs. All of these things, including ambient room temperature/ventilation, can have an impact on bulb life. I've had some T5 going on 2 years now, and others that burnt out (completely) in 6 months due to heat.

[Ghazanfar Ghori]

If I remember correctly, T5s are in the range of 20,000 hrs of use.

[Aaron]

With proper reflectors and ventilation they can last a good 2 years of use. I like to use fixtures with two separate banks of lights and have some come on for all 10 hours of a photoperiod and the others come on for only 5 hours of a photoperiod. Then switch which bulbs do what duty every 6 or 12 months and over a two year period they should get equal use and last longer.