i had the same problem with my 29 i would replace the filter cartrige 2 times a week, so many times i would get a phone call from the wife saying your tank is going crazy making noise and shooting out bubbles and i would tell her to unplug till i got home i lost fish and corals due to stress you can turn the filter cartrige so its not blocking all the water or lay it on your bio balls or remove it i removed it right when i found out the problem that way your water can go to the top where your pump is. hope this helps