I have been using a 36W turbotwist for a while now and it works excellent to keep green water in check. The construction of it is another matter. Ive had the unit blow a bulb new. I mean blown. It leaked out the gas out of the tube and it must have burned because the inside of the quartz tube was a burnt brown. Also Ive had the plastic barbed fitting crack and leak so I ended up gluing the plastic together to fix. It works but is deeply flawed when it comes to durability.
UV will degrade a plastic housing from the inside...just like a plastic chair out in the sun....