what kind of filter

the penguin is good, but id reccomend an emperor, much more powerful and also has the bio wheel, and it has a seperate media basket so you can add whatever you want. i love my emperor 280 on my 29 gallon

I've got a Penguin with a bio-wheel, it's great. AquaClear filters are nice, they're very versitile, but sometimes get noisy after a few years. I've heard nothing but good things about Emporers.

I used to use an Emperor 280 before I switched to a Rena Filstar XP-2. I only switched because I started using CO2 for plants. I'd say that if you're thinking that you may wanna go all out and do a highly lit and heavily dosed planted tank (which I can assure you isn't for everybody), the Emperor would be a great filter for you. People speak highly of Aquaclear as well, but I've no personal experience with the brand.

If you think you may want to have a planted tank with a requirement for co2 to be added, save yourself purchasing two filters and look into canisters. They can be had for only a little bit more money.

Sam