Pardon my ignorance re: cannister filters :D

[dsmalls]

I guess I just don't get it. Seeing as I've never owned a cannister filter, I have a question or three:

1. They are generally used for aquariums >= 40 Gallons. (T/F)
2. Can you adjust the out-flow?
3. For larger tanks (55g +), would one cannister provide adequate filtration or would/should you use two?
4. My HOB's (TopFin 30) use charcoal with 'cotton' waste trapping stuff, does a cannister have something similar that needs to be changed/cleaned on a regular basis?

As always, thanks!

[oscarbreeder]

1. True(for the most part)
2. Yes you can adjust the flow.
3. It depends on what type fish you are keeping. (I use two on my180gal)
4. Yes, they have media trays in them that you can add different media to and they will need cleaned/changed.

Hope this helps.

[shawmutt]

1. Well, it depends on your preferences really. I have a Filstar XP1 on my 30 gallon. They are only rated at 250 GPH, probably closer to 200 GPH with the correct maintenance. There's HOB filters that have a higher GPH. I prefer the canister because it has a low profile, much more surface area for beneficial bacteria, and IME is much easier to maintain.