I tried this using polyester filling as filter floss for one month. It was
a disaster. I would probably have had better results not using anything.
Although ammonia, nitrite, nitrate, pH, gH, and kH levels didn't change the
water quality definitely changed for the worst. Some sort of very fine
particles were suspended in the water and I had algae problems on a scale
I've never had before. The "fine particles" disappeared after I switched
back to the manufacturer's filter cartridges and after scraping the algae
off everything, that hasn't returned either.

That said, lots of people have had success with this stuff. Try it. Its
cheap. You probably won't hurt your fish. But switch back to real filter
floss if things start going downhill.
E.Otter