I use felt and it helps with the bioload. I have 30 and I change them sometimes daily then at the end of the week throw them in the washer and they come out clean.
My felt ones keep clogging up on me and creates a terrible issue. The water in the return starts to back up, then the sump gets low, triggers the ATO and before I know it the ATO has pumped in a few gallons of fresh water. I don't mind changing them weekly, but every two-three days seems like a lot for someone who feeds once a day.