Yeah my 20 gallon has been running on 2 penguin minis for about 6 months now.(I originally had one but it broke and i bought another but then i found out there was just some debris in the motor and i fixed it) So i though bigger is better and i have 2 of them running. But now im debating on wether to change to another filter because i notice the performance is starting to decline and i was in the mood of changing them anyway. Any suggestions? The fish I have in it are a pair of breeding marigold swords, 5 upcoming babies(about an inch long each) and a betta