The best chillers on the market are Pacific Coast Imports, I've read several articles that state the same, I've had mine for 2 years now with no problems, I just set the biult in controller, more other brand you have to have a seperate control, so I just set the temperature and leave it, I flush it every 6 to 9 months, and it keeps my tank with in 1 degree of the set temperature 24 hours a day, 7 days a week. Also, very important, I run 3-400w MH and when I added the chiller I only noticed a $3.72 a month increase in my electric bill. You can goto www.pacificcoastimports.com for complete information.
Eric