EHEIM - EHFISUBSTRAT replace ??? why ???

"When changing the filter medium use approximately 1/3 of the used,
uncleaned material again in order to support the new development of
the bacteria"

I can understand not wanting to replace the entire volume of the
EHFISUBSTRAT and wiping out most of your bacterial colony. My
question is why would you EVER want to replace the material at all? I
didn't think of this material as clogging like the filter pads, but
does it clog? Does it deteriorate? Does it really need to being
periodically refreshed?

And what about the really coarse EHFIMECH (those hollow cermic
cylindrical thingee's). Do those ever need to be replaced?


Ummmm to get you to buy more perhaps???

Seriously, Ehfisubstrat is sintered glas & has thousands of tiny pores in
it. Inevitably over time these will get clogged. That said there is still
more than enough surface area in the filter to provide more than adequate
bio filtering. You don't need to replace it as long as you keep it
reasonably clean. When I clean mine (and I have two 2224s) I just immerse
the basket in a bucket of tank water & give it a really good shake from side
to side.....seems to work just fine. Couldn't do any harm to replace half of
it once a year or so......

I.