Case of the Rio often crack. Water got into the coil of the motor. If you don't have a grounded tank with an GFCI outlet for this power head, the pump keep on running and dump copper into the tank and kill the whole thing. Do a search with Rio and tank crash, you will find plenty of people with this disaster. I learned this the hard way 6 years ago and documented in a thread about 6 years ago. I tried to find this thread but not able to find it.
Rio pump is very cheap and powerful for the price. Not every Rio pump will toast your tank, but enough of it will. Save 20 dollars and run the risk of crashing your tank just not worth it IMHO. GFCI outlet is extremly important. Salt water with electricity is a dangerous combination. I am sure GFCI saved moor than a few reefers's life and save a few house from burning down.