This time the problem is it's sucking in air from somewhere, but is not leaking water. I'm not sure where from, as all the o rings seem in place. I've tried shaking the filter to get the air out, but as soon as it's expelled it, more appears in the cannister from somewhere. I'm assuming it's got to be somewhere on the filter end of the inlet pipe. I've got a constant stream of bubbles from the outlet and a noisy impellar that is really annoying!