This is as complicated as you want it to be, actually.
Most of the commercial filters that you can buy from retailers are designed to work with minimal setup and hassles. Most that you buy do not require drilling tanks.
The magnum HOT style cannister filter hangs onto the back of the tank and dips into the tank for suction and return. The Magnum 350 is a canister that sits on the floor and moves more water than the HOT. They come complete, with a multitude of accessories, biowheels, quick connect fittings, everything you would need to filter a 55
gal tank.
If you visit
http://www.marineland.com/ you can read all about the differences in filters, media and applications.
If you don't like the shake-and-bake aquarium setup, the the sky, your imagination and your wallet is your limit. And this is where things start to get complicated. Much more so than I would like to elaborate here.
The marineland Tidepool filter is similiar in application to a wet/dry filter. A wet/dry filter could require a seperate sump and return and then you have things like syphons to worry about and making sure your sump is deep enough to hold all the water that comes out from the siphon when you loose power to the pump. Of course, then you have to restart the syphon one you return the pump to operation.
When you hit the LFSs, look in the upper corners of their tanks. Chances are, a lot of shops use drilled tanks that negate the need for a syphon. These come under a lot of different names, bulkhead fittings being the most common. Ask them, who locally drills tanks.
If you are couragous (or just a
DIY'er) then google is your friend and see other aquarists solutions. I've drilled two tanks myself, with a diamond grinding bits, steady hand and lots of water from a garden house (to keep the glass cool and wash away the bits).
Another solution is to drill the bottom and use a stand pipe. This is mostly in the corner of a tank and the corner is sectioned off by a skimmer so that your fishies wont find it.
You'll find a lot of these type filter setups with Saltwater tanks. Again, google it.
I set up a 10g nano reef tank for a friend in an apartment this way, using another 10g as the sump. This effectively gave him 15g of water to play with instead of the 10g (not counting rock volume). Having the sump under the main tank also reduces the footprint of your aquatic adventure (insert, happy spouse).
But, do your fish require this elaborate of a filter system to live a long and healthy life?
That is a question that will always remain an active debate.
