LOL...I used an Azoo sponge filter, the Bio-Filter 11 also, in my 5 gallon tanks. The first filter that I got for these 5 gallon tanks was an Azoo Bio Filter 3, I think it was. It was much too big for a 5 gallon tank! It sure didn't look that big in the picture. You'll like that Azoo Bio-Filter 11. The little hard tubing where the airline attaches will pull out of the filter for maintenance. You only have to connect the soft airline tubing once. Rinse the sponge periodically and attach the short piece of hard tubing back into the filter easily. That's a lot easier than trying to push the soft airline back on every time you do filter maintenance.
I bet DrsFS will waive the shipping charges on the new filter. I ordered a ball valve once from DrsFS and it was too stiff. I almost hurt my hand trying to turn it. I called and they sent me a new one and didn't charge shipping.