I have an Aqueon Quietflow20 filter. It has a cartridge filter with some white filter material and carbon in it. Instructions say to replace it monthly, but what I am understanding from reading in the forum that I am to just swish it in used tank water to get rid of some of the debris until it is absolutely clogged and then try to get two cartridges in there for a couple of days before removing the old one. Is my understanding of this procedure correct?