poor filtration

Question
Hello Chris,
 I've got a bit of a dillema, I have a fifty gallon breeder.In it I have 2 musk turtles and various fish. I've had my turtles for over 20 years. I bought a Magnum 350 filter a few years ago and it doesn't seem to keep the water as clean as my previous smaller older filter. The water quality is fine, My fish are almost all sexually active, I haven't lost a fish to disease in years, but the water is brownish/yellow. I clean on average every three months with regualar water changes. I know the turtles are filthy, but in the past my water was clear. Could my filter just be to small. I also have a submersible fluval 4 filter head as a power head for a 12"x12" under gravel filter. That alone pushes enough water to circulate the tank three times an hour. I have more fish than I want in there but they refuse to rotate out. For example I have a pleco that is about 13 years old I'm just looking for someone who has experience and I can bounce questions off of. The folks who have contacted you seem to appreciate your advise, so I thought I would give you a try. So again why if I have two filters that circulate my tank more than is required is my water yellow? Thank you.

Answer
Chris has been unable to answer your question due to computer failure. You can ask another volunteer expert or post your question on the forum at our sister site About.com in the freshwater aquarium section. There are many knowledgable members there that should be able to help. The website address for the forum is;

http://freshaquarium.about.com/mpboards.htm

Thank You for your patience. Chris should be available again in 2 weeks.