The NYOS Viper 3.0 (I think I got the 3.0) works very well and provides a 25% increase on flow compared to the original Sicce circulation pumps. The drawback however was the short power cord. If you don't mind having an electrical extension hanging off the back of the tank, then it's no problem. For me the back has to be 'clean' as it is on display, therefore I couldn't replace all the pumps with a NYOS.