I have a 20 gallon bowfront aquarium about 8 years old that came with an 18" flourescent light fixture. I'd replaced the tube on average every two years, or so, UNTIL lately, it began to burn out a tube every month. I'd returned two tubes to Wally World, with no arguements, but the latest tube, a GE, barely glows. So, rather than continued treks to Walmart, I wonder is the fixture itself is the problem. Taking it apart, it seems there's no replaceable ballast, just a square transformer thingy. So.... the question. Is it logical that the fixture itself is the problem? I can't believe "they" want around 40 bucks for a replacement fixture on line. Anyone else with similar experiences? Thanks, Ron.