far as i know, ceramic beads last indefinitely. they keep working unless the pores get completely clogged up with some sort of toxic slime. then you could just boil them and they would be good to go again.
how do i like the magnum? i wish i had planned the placement a little better. i plan on moving it to another tank, so i am putting up with the inconvenience because its temporary.
i end up taking it apart once every 10 days to 2 weeks or so.
the blue sleeve is pretty gunked up by then. its probably due to overfeeding. but the stuff on the sleeve looks like poop, not food. other people state they can go a month without servicing their eheim/ fluval cannister filters so the magnum appears to be more work.
i've had it running for 3 months maybe and the blue sleeve is starting to stretch out / wear out. i think i can make a sleeve from some cheap filter material i picked up at my lfs. that will save some money.
i'd say its doing its job, but $40 more spent for an eheim, might have been a better investment.