You can create a bio-filter out of any number of things; plastic storage tubs form Wal-Mart, aquariums or you can purchase one. You just need to make sure it is the correct size for the amount of Nitrates that has to be processed. As of the worms, I have in the past but after having to spend almost a week cleaning up the mess in addition to my system being non-operational all that time, the answer is an emphatic NO..!