Last year I sold my 500 litre sumped marine tank [soft corals, copperband butterfly, flame angel, etc] and replaced it with an Aquael 240 litre freshwater tank, filtered by a Oase 600 Thermofilter canister.
This had nothing to do with preferring freshwater to marines, just downsizing now that I'm getting [very!] old.
I found that the sump filtration, which I had for about 13 years, was a bit leaky, noisy and needed constant topping-up, despite my cover glasses. However, it was also very flexible in terms of the different media I could use, hid equipment like the heater, and enabled me to grow caulerpa as a filtration aid. I kept a Copperband Butterfly for over 8 years, for example, and it was still a picture of health when I traded it back to my lfs.
Now, with my Aquael 240, I rely for filtration on the freshwater plants I'm growing, and on my canister filter. It contains a heater, and also a prefilter, which is very clever; I clean it every week, and the main filtration in the canister doesn't need to be touched for about 6 months. It's very quiet, especially now that it's been run-in for several months.
My conclusions for freshwater tanks are these; if you can build your own quiet, non-leaky sump to a high specification [beyond my DIY abilities I'm afraid] then it's the bees' knees of filtration - especially if, as others have suggested above, you use fluidised K1-type media in it. Otherwise, the latest canister filters are a great off-the-shelf option, especially if you can get one with a prefilter, as both Oase and Aquael offer.
This is not to denigrate Hamburg Matten-filters, or even the humble sponge filter, though these often need a fair degree of hiding from view.
This is my Aquael 240, in its early stages; bit more of a jungle now!
