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Plenipotentiary-at-large
We're getting smarter...
All good advice...as a rule, never replace filter media/cartridges/pads/etc., just rinse and roll. The only thing useful that most of them do is afford colonization sites for bacteria and that takes time to establish. Medias with charcoal are effectively no better than any others after 48 hours although the charcoal does function as a great site for bacteria to inhabit long-term given it's semi-porous/interstitial nature.
Bacteria never sleep, are ravenous and live to make more of themselves - that "dirty" stuff in your filter is largely inert excepts for its complement of beneficial de-nitrifying bacteria because all the ammonia/nitrites will mostly have already been converted to nitrates - it's organic but just barely in that there's nothing left in it any longer that can hurt your fish. Most tanks do not have sufficient bacteria to break down nitrates so that they outgas from the system by themselves as nitrogen unless there is a deep (3"+) substrate that allows for the anaerobic conditions that they need, which is why we do water changes to export nitrates. Essentially there's nothing in an established filter that is harmful per se (the exception to this is if the media is so clogged that it impedes or restricts water flow) no matter how "dirty" it seems to be because it's all part of the same water system and the concentration of waste in the filter is effectively no higher than any place else inside the tank system.
Surface area (any) for colonization is the key, and much more important than flow rate which is why slow-moving water flow through a filter with a sponge pre-filter and/or bio-wheel and/or lots of internal media is better than high flow through sparse media. Whatever filter you're using , a semi-coarse (pond) foam/sponge pre-filter on the intake and supplemental foam pads, charcoal, lave rock, etc. on the inside will boost the ability of the system to rapidly process waste. Sponge filters typically have very low water flow, but their output/waste processing is superior which is why they are the foundation of most fish rooms.
All good advice...as a rule, never replace filter media/cartridges/pads/etc., just rinse and roll. The only thing useful that most of them do is afford colonization sites for bacteria and that takes time to establish. Medias with charcoal are effectively no better than any others after 48 hours although the charcoal does function as a great site for bacteria to inhabit long-term given it's semi-porous/interstitial nature.
Bacteria never sleep, are ravenous and live to make more of themselves - that "dirty" stuff in your filter is largely inert excepts for its complement of beneficial de-nitrifying bacteria because all the ammonia/nitrites will mostly have already been converted to nitrates - it's organic but just barely in that there's nothing left in it any longer that can hurt your fish. Most tanks do not have sufficient bacteria to break down nitrates so that they outgas from the system by themselves as nitrogen unless there is a deep (3"+) substrate that allows for the anaerobic conditions that they need, which is why we do water changes to export nitrates. Essentially there's nothing in an established filter that is harmful per se (the exception to this is if the media is so clogged that it impedes or restricts water flow) no matter how "dirty" it seems to be because it's all part of the same water system and the concentration of waste in the filter is effectively no higher than any place else inside the tank system.
Surface area (any) for colonization is the key, and much more important than flow rate which is why slow-moving water flow through a filter with a sponge pre-filter and/or bio-wheel and/or lots of internal media is better than high flow through sparse media. Whatever filter you're using , a semi-coarse (pond) foam/sponge pre-filter on the intake and supplemental foam pads, charcoal, lave rock, etc. on the inside will boost the ability of the system to rapidly process waste. Sponge filters typically have very low water flow, but their output/waste processing is superior which is why they are the foundation of most fish rooms.
