I have now for a year an aquarium of jewel. And have in the filter also the nitrate remover with it. Whether it is at all from the outset with at, I do not know. For me it was like this. And I had until now no problems with the nitrate value. Always go to the greens. While it is always exactly at how many times you have to replace the individual filter media, but I have all always a deadline. To after half a year to be exact. Some you have to change more frequently, some can also stay longer in it.
A little tip: all filter media (except cotton) take 2-3 weeks to get out and rinse thoroughly. That's enough when cleaning. And if you do not really get clean, then replace. The Filterwatte really should be cleaned every week and renew every 2 weeks.
That was more than just my experience with the nitrate remover, but the individual parts are so important for all good water values.