Can't fault the flow rate of this pump and have had to put a dimmer switch in to slow it down a little even though it's running through a pressure filter. Keeping the pond very clear so far though but yet to see it's first summer. The only moan I would have is the wattage isn't stated by the seller and at 420 watts it would be quite expensive to run flat out 24/7. Hopefully my dimmer switch will even this out a little though!!