There were a few people lately ask me about how to set up their own aquariums, it was their questions that prompted me to take this approach rather than the
"here you go, get a 200L - 400L tank, a canister filter with 1000LpH - 2000LpH flow, medium size dark gravel, basic T8 lights, as heavily planted as you can afford, and cycle it using live liquid bacteria and a few fish. Do a water change 25% a week."
Now I plan on saying, if you want a smaller tank, expect problems. Water parametres and spikes, algae blooms, etc. More water = good.
If you want to use a small internal filter, you will get a lot of flow, but not a lot of biological media. A sponge filter takes up more space inside the tank, but has much more bio media. A canister or a sump is the best way to go, it's quiet and it's outside of the tank/display area.
If you want to do a fishless cycle, which to some people is more humane, the you need to find the right type of ammonia. Cloudy ammonia is Cloudy. If you want to do a live fish cycle, keep the water changes up. Be vigilant. If you can get bio media from a friend, GREAT, but keep an eye on it and start stocking slowly.
If you don't want live plants, that's fine, but the more the merrier.
See? Not huge, but I do plan on expanding it a lot.