my penguin 100 is officialy getting the boot! last night it made so much noise(not water returning something with the impeller) it was scary! being it was 3 in the mornin i just turned er off and threw the biowheel in the tank. so in the morning i got up and went and checked the filter out. took it all apart and not a single problem. so i figured mabye the impeller needed to be washed so i washed it and restarted it. than it made just as much noise as last nite so its done. im buyin a new AC, which model would be good for a 5.5 gal beta tank?