Fluval fx-6 would be a great option. I haven't had good luck with aquatop canister filters.
I agree with Wailua Boy. I recommend at least 20% water changes every week. But it also depends on how big your RES are. Considering they could be 1 inch to 20 inches in diameter.
a single fx6 filled with bio is enough. key for turtles are
daily water changes because of their large bio load and
scute shed. doesnt have to be a large water change just
siphon the bio load and scutes out and top back off.