Originally Posted by mfdrookie516
Replace it when it falls apart... no sooner or you're wasting money.
That includes the biomedia (biomass) that mfg will tell you to replace every 3 months, this should never be replaced since your good bacteria live/breed in it. Just rinse it out in old tank water during a PWC
(same with sponges) once a month (+/-).
The only exception is carbon, if you use it (I don't unless I'm removing meds). It should be swapped out every 2 weeks or so because it can cause problems if it's left in too long.