Read this one with interest. IMO an established filter will more than cope with your tank if it is correctly sized, as it is "fed" on a continuous cycle. That said if you suspect problems then the use of this aid is justifed, but as an ongoing additive to the tank going in regulary, well to be honest really dont' see the need for it. 

but the water is lovely and clear as before when done wter change water would be a bit cloudy for a day or so , so for that think they are great . I have put 4 balls in new filter to help boost plus 5 in tank so all crossed