I have an external aquarium pump
http://www.zooplus.ie/shop/fish/filters_pumps/canister_filters/eheim/133666
I have replaced it as it had a tiny leak - the leak is about one drop every 10 seconds or every day it would fill a teacup - it annoyed me - perhaps this pump would work well as part of a brewing cooling system - in conjuction with a plate chiller
either way - I dont need it - willing to swap it for 5kg of pale ale malt !
Any interest - it gathering dust in the shed.