[bean]

hello im new to forum but not to cresties i have two adults and have a question about waterfall.....i already have a exoterra waterfall that needs water changing every two days really which is a pain,i have been looking about and seen that lots of people use hydroballs and pump for waterfall and it also acts as filter .....now am i missing the point or could i just put hydroballs in waterfall around pump and it would act as a mini filter for waterfall??? havent seen this done and was wondering why?? balls are to big to get sucked into pump and they say natural filter so why not?? thanks.