I personally just take the sponges out once every 1-2 weeks and wring them out in water change water to remove all the waste and stuff and to prevent clogging, but DO NOT TOUCH THE BIOMEDIA, EVER. The most you should do is maybe use some tank water to LIGHTLY rinse off the poop and stuff. That is what I do, some people clean once a month and do the same thing, some just wait until the filter is clogged/too dirty, I just do small, frequent cleanings as a few sponges in my filter get clogged within a week. So to sum it up, just wait and see when the filter sponges and stuff get dirty and look brown and gross, just wring them out in some tank water from a water change and put them back and do that as needed, if the biomedia gets really dirty then maybe use a bit of tank water to rinse off the waste (with something like a turkey baster as to not disturb the media too badly).