What filtration system works for your turtle?

[Boots]

I am currently using a Zoo Med 501 filter for my red ear sliders, and am looking to upgrade to something that actually keeps the tank clean. While they advertise the filter as made for turtle, it does not really work as advertised once the turtle are about 3 months old.

I used to use a Fuval 403 and it did a good job, but I would like to know what everyone else is using, and what they have found that works for them. Any suggestions are appreciated.

Jason