How many filters do you use???

That's very good advice about two filters. Never seen anyone do it but it is a very good idea especially in a bigger tank. I have smaller tanks and I use one sponge filter but I have read that it is a good idea to run two filters in case one goes kaput or to have another ready to go in case you are setting up a new tank. The extra one gives you a cycled tank all ready to go.

 

There is at first glance apparent logic to having two filters instead of one, but it is not something I would ever do, unless it was a very large tank (say, 8 feet in length). There is a lot of misunderstanding in this hobby about filters and filtration, and this only feeds that.

An aquarium should not rely on the filter to survive. If it does, there is a serious problem. Stocking the aquarium properly for the water volume means it will manage without the filter if it should fail. The prime purpose of the filter is to create water movement and keep the water clear...which is a very different thing from clean water. Once the aquarium beecomes established (not just cycled but established) there will be more bacteria and more different species of bacteria living in the substrate than in the filter.

The other thing is that the filter should always be suited to the needs of the fish in terms of water movement. Fish are affected by currents, just as they are by light, the "decor," and other fish species.

Larger filters or more filters have no benefit to filtration, provided the tank is biologically balanced to begin with.

 

My 3 tanks are all lightly filtered and have sponge media. From a biological perspective I am really not worried about failure. I have a spare sponge filter and air pump I use for my QT and another small spare filter that came with a new that I never used. If a filter fails I'll just swap it out and re-use the existing sponges.

 

Im running a Penguin 350 and a sponge filter in a 40 breeder. Overkill yes but if i ever lose power i can run the sponge filter off a battery backup air pump.

 

I am using an under gravel filter in my 55 gallon tank for now.