Short in my fixture from spitting fish...

[Binare]

I use workhorse ballasts along with GE 10k bulbs.

The GE bulbs are rated at 25,000 hours lifespan. and are 95% efficient at 40% of there lifespan.

I run my lamps 10 hours a day, which works out to a 2500 day life span (average) or almost 7 years. Take into effect the efficiency (95%@40%) and I change em roughly every 3 years or so.

They cost me about 3-4 bucks a piece. 17 bucks per ballast.