Original: Typical flow is at 0.5 metres per second ( 1 â '' 2 feet per second ) , and can be as fast as 2.5 metres per second ( 8 feet per second ) .
Simplified: Typical flow is at 0.5 meters per second ( 1-2 feet per second ) , and can be as fast as 2.5 meters per second ( 8 feet per second ) .