taken from another thread:
If you want to save some money........on the same pump without the brand name of Sedra, Dolphin, or Senn on it, buy it here a lot cheaper....
Non-branded
These are the same pumps everyone is brand naming and buying from China. They don't sell the pin impellors though. You can get a spare or replacement pin impellor from FishSupply for about $35 for the Sedra 9000, if I remember correctly, and still come out ahead. The WP4 is the same as a Sedra 9000 and I believe will accept the 9000 pinwheel impellor.