One of the big advantages of having two filters is that you can relegate one filter to primarily mechanical filtration duties and one to biofiltration (a technique learned from RTR; I don't claim to have stumbled across it myself). My biofilters are rarely cleaned (except for whisking off a prefilter sponge and rinsing it -- about a 3-4 minute process, tops. Otherwise, the biofilters are mostly canisters and they are packed with bioballs or ceramic noodles that are pretty much self cleaning. A second filter is for mechanical filtration, and I don't worry about being careful with the media and any beneficial bacteria it may contain -- the good bugs are preserved in filter #1. Mech filters are selected for max throughput and ease of cleaning (and ability to use longlived media, like sponge, rather than expensive cartridges).
Of course bacteria live on all surfaces in our tanks, but they'll be densest in the places that are most hospitable: zones with lots of colonizable surface area, with constant circulation of water containing food (ammonia/nitrite) and oxygen. That makes the inside of a biofilter hard to beat for a bacterium.
Tanks could certainly be stocked lightly enough to not need filters. If you can turn them off for weeks at a time just for kicks, why have filters at all? Why not save the money? Seems kind of pointless to me...
Anyway, it's easy to show that bio-only filters are preferred sites for bacterial colonization. Just take a bio-only filter that has been running on an established, healthy tank with X number of fish. Set up a completely new tank, load it with the same volume of fish, and see what sort of ammonia/nitrite readings you get -- most likely, you'll see zero. Try that with the tank from which the biofilter has been removed, stocking it equally. You'll almost certainly see an ammonia/nitrite spike.
Finally, that idea that any filter takes as long to clean as any other is ludicrous. It take substantially longer to clean a canister filter, which you must disconnect, open up, clean media, clean housing & impeller, reconnect and reprime. I can clean three or four HOB filters in the time it takes to clean one canister.
HTH,
Jim
Of course bacteria live on all surfaces in our tanks, but they'll be densest in the places that are most hospitable: zones with lots of colonizable surface area, with constant circulation of water containing food (ammonia/nitrite) and oxygen. That makes the inside of a biofilter hard to beat for a bacterium.
Tanks could certainly be stocked lightly enough to not need filters. If you can turn them off for weeks at a time just for kicks, why have filters at all? Why not save the money? Seems kind of pointless to me...
Anyway, it's easy to show that bio-only filters are preferred sites for bacterial colonization. Just take a bio-only filter that has been running on an established, healthy tank with X number of fish. Set up a completely new tank, load it with the same volume of fish, and see what sort of ammonia/nitrite readings you get -- most likely, you'll see zero. Try that with the tank from which the biofilter has been removed, stocking it equally. You'll almost certainly see an ammonia/nitrite spike.
Finally, that idea that any filter takes as long to clean as any other is ludicrous. It take substantially longer to clean a canister filter, which you must disconnect, open up, clean media, clean housing & impeller, reconnect and reprime. I can clean three or four HOB filters in the time it takes to clean one canister.
HTH,
Jim
