Thanks for the input, mine are all 2 to 3 years old and still bask. The largest(id say around 8 inches) I still see bask atleast once a week. My question is would the Fluval 4 for good enough for 100 gallons of water? Or do you use multiples? Bescause I have I believe a Fluval 4 in the smaller indoor pond(which is only 40ish gallons) with my RES and Cooters and it still need a frequent water changes and filter changes, more then my other filters.