Thanks Victor, it was the noise really with the supplied media balls. Read many threads suggesting no media but I need something as there is bypass without. I am worried about the media blocking the out pipe so suggestions as to how many bath scrunchies are welcome.....im guessing finding a balance of too compact (reducing flow) and too loose (threat of blockage) will be slightly trial and error.....will get a few and try. Maybe cut up cubes of filter foam may work also. I won't mind cleaning it if it is quiet and effective