Yeah I would say that when you add the water into the tank, just add it slowly and try to have it "hit" something on it's way down ... like pouring it against one of the sides. Also, do you have a tap that doesn't have an aerator on it? My kitchen tap and bathroom sink taps DO, though my bathtub does not. Maybe check out your bathtub faucet (if you have one) to see if it does the same thing? (sounds silly but you never know lol)
