Hi Lee
I use washing machine pump as an auxiliary pump in my fish tank external filter - very high flow, and can push dirty water through few thick layers of sponge but it can't run for too long - it gets really smelly hot. I don't remember pushing it more than for hour- then you can smell it in a whole room.
Edit: I use CH pump to pump coolant in my milling machine- works excellent, high flow, good preassure to flush chips away- those pumps are reasonably priced eg. at toolstation or scewfix