Proper water filter for 20 gallon TURTLE tank - waters too merky?

Go with a canister filter oversized as you will use it when you upgrade your tank size...get one for a 75 gal tank or bigger as you will be needing that size to keep the water nice and clean.Big Als has the best prices around I have found for canister fliters...I go to the Whitby store for any filter purchases and both my tanks are clear and the levels stay good for several weeks at a time.I have a Rena XP3 and an Eheim canister for my two 75 gal tanks and they do a wonderful job.