Turtles are messy animals. The better the filtration, the cleaner their water will be.
It is important to remember that turtles eat, sleep, urinate and defecate in their water. To keep your turtles in good health, regular partial water changes are recommended. The easiest way to do these are by using an aquarium vacuum to clean the bottom of the tank and then top up the water level.
There are many different types of filtration available. One of the easiest to set up and maintain are external canister filters. Like most things, you get what you pay for. The better quality filters are more expensive, but to a better job.
Any filter will be more efficient if you set it up so that it draws water from one part of the tank and returns it to another part of the tank. This way, the water will be continuously circulated.
