Tim, I have an Emperor Aquatics Smart UV model #02040, it has a 40 watt bulb....My 240 is just over 2 months old, I use tap water, and I have almost 0 algae growing in the tank already.....I really think it is solely due to the UV as when I first started the tank cycling, I had a crack in the sleeve of the UV, thus it wasn't working for the 1st 10 days and the brown algae was out of control, as soon as the UV fired up, one good scraping, and the brown algae has gradually decreased to almost nothing....It wasn't cheap, but worth it I think.
Sorry Matt, but I would definately disagree....not a gimmic