The very fact that your ceramics look particularly filthy means that the dirt will have clogged all the pores reducing their ability to home as much bacteria, If adequate mechanical filtration is used prior to the ceramics they will remain more efficient for longer and you will only ever need to clean the mechanical filtration, I know it will be hard for many to accept any change especially is they have run a set up for a particular length of time and have good water parameters, but this way pretty much eliminates the chance of any spikes occurring!
