i was told in the past that my fish where having problems because i did a water change and put a new filter in wich killed the bacteria colony.so since then i have been shaking the filter out in a 5 gallon bucket of the tank water like i was told to.It has been about to months since the last time i changed it and do to the slight overstocking is building up a good amount of slime.My question is when do i change it to a new filter and how do i do it without killing the bacteria?
