Answer: -Liquid Plumber ... or the Tweaker's favourite, Red Devil Lye. -I recommend Plumbline Services ( www.plumblineservices.com ). For a flat fee, they will give you a quote on how much the service will cost. I haven't used them, but they are on Tom Martino's recommended list. I have used Marta Mechanical ( http://www.american-plumber.com/profile/heat/CO/Boulder/592 ) in the past, but I'm guessing they might be a bit more expensive. They provide a good service. Whoever you use, ask them about regularly using enzymes to maintain the general health of your pipes.