I've tried googling and searching past posts already and have tried those suggestions but my filters are still noisy.

I have two tanks, each with an ocelarris 400 external filter. On both I can hear a rattling noise. They're marketed as being extremely quiet which I know is probably not quite true but this is irritatingly loud if I'm even just sitting in my room. They're too loud for me to go to sleep so I either have to turn them off or wear earplugs.

I think the problem is that air is getting trapped in the filter but I've tried shaking the canister until no more air comes out and it's still noisy. I do have an air pump in one tank temporarily until I remove the sponge filter but there's nothing in the other tank making bubbles. I've vaselined the impellor and around where the head unit goes on but that hasn't made a difference. I've also taped insulation tape around where the pipe joins the canister and the inlet/outlet pipes to try and tighten those seals. Water can seep from the join of the main canister and the head unit if I tilt the canister so I don't know if that's where air is coming in?

I took a video of the noise although I don't know how well you can hear it. Pictureof the filter.

I don't know what else to try!

Edit: think I've fixed it now, it's a lot quieter! There's still a small rattle but don't think I can get rid of that. Put insulation tape on the hard plastic bit that goes in the hose. Which is what my LFS suggested but I taped the outside rather than the inside... Bit of a stupid moment I think! Was hoping the pressure of the tape on the outside would tighten the connection enough.