Did you take the pump apart? If the pump is pumping the correct amount of water than something is restricting the flow. There are very few places that water flow in an Aqua C remora. Follow the flow starting with the pump and check for blockages or malfunctions.
I inspected it with a light today thinking that was the problem, but the bubbles are going right under the last bottom baffle up & out of the return area.
It's been running on my tank for almost two weeks but I bought it used, the inside is full of feather duster tubes? Funny thing is, I took it off yesterday, then decided to put it back on last night, this morning, no bubbles! Let's see how long that lasts.
Maybe it was something like the glue from some of the frags I added, or I think at least 1 of them has epoxy. Also, my arm constantly in the tank.