you have a hole somewhere.
unfortunately the easiest way to figure out where the air is getting in is to let it run for a few weeks. in that period of time you will start to see
salt creep growing around the hole.
how fine are the bubbles? if they are very fine then the hole is prolly before the pump. if the holes are not super small then the hole is prolly after the pump.
mags can be leaky around their volute. have you checked the rubber seal around the volute? when taking off the volute, you need to be very carefull not to break the ceramic shaft and strip the plastic towers where the screws to in.
G~
