Jim Morcombe said

How long does the filter wool last before it needs to be changed?

Do you clean the filter wool and re-use it or do you just chuck it away each
time?

Don't use filter wool, instead use sponge. This will last ages (a year
or more) and it certainly should not be thrown away as this is were your
friendly bacteria will be living. You just clean it as required in old
tank water - I do mine at the same time as a water change.


Do they work? Is it worth using?

Yes and yes - depending of course on your set up.


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