I have a 55g tank up and running for almost a year now but the filter i got didn't come with the bio wheels. To buy new ones its almost 25bucks when i can get a new filter for 39.00 on sale. I was wondering would it be over kill to run two penguin 350 filters for a well stocked 55g tank? I just get worried when i rinse my filters that im going to take to much bb and start a mini cycle. i put two little sponges behind the c filters for safety to grab more bb. I never had problems yet with ammonia or water quality.