I'm not super happy with the life of these bulbs. That said, they do the job, and the Turbo Twist units are great.If you're thinking about running UV continuously for the sake of general water purity, consider that it's not necessarily to do so with most aquaria. We ran continuous UV for awhile but found that replacing our carbon with Seachem Purigen worked as good or better at removing organic impurities in our water. Purigen polishes the water amazingly well, even where some algae is present. Plus, it's renewable and lasts 5-10x longer than carbon. Now we only use UV if one of our pets is ill (rarely), which keeps us from buying UV lamps every few months. It's sooo much less expensive this way.
Rating: [3 of 5 Stars!]