I've got 3 african clawed frogs in a 180 litre tank (according to Google that's 39.5944 imperial gallons or 47.551 US gallons), and I might be adding more frogs in the future. At the moment I'm using an internal filter (the one that comes with a Juwel Rio 180/240). The vents are at the top of the filter box so it doesn't really filter any of the waste that gathers at the bottom of the tank, but it does keep the tank cycled and keep the water clear. I'm thinking of either replacing it with an external filter or running my Juwel filter alongside an external one. I've only ever used internal filters so I don't know much about external ones. Is it important to get an external filter that is intended for a larger volume of water than I have in my tank? Could I get a less powerful external filter if I keep my internal filter in there too (I'm trying to spend as little money as possible)?
Can anyone recommend a good external filter? I'm looking at Fluval filters at the moment, purely because everyone seems to have them so I assume that they must be good. If I get a Fluval filter, what size would be best for my 180L ACF tank?
Also, does anyone have any experience of them leaking? I'm a bit paranoid since I live in a first floor flat.
Thanks.