I have a WP-10 in my 20g long and love it. It creates excellent flow and there are almost no dead spots. However it only has 3 speed settings and even at the lowest setting its kind of too much flow for some of the softies. But I am focusing more on my SPS so I don't mind. For people looking for a new powerhead for a small tank, luckily Jebao has a new wavemaker that replaced the WP-10. Its the RW-4, and the speed settings go all the way down to 10%. Its also slightly smaller.