Just thought I'd add a review here... you can't get penguin biowheels, aquaclears etc. here in the UK so I thought a review of a good filter which you CAN get here might be useful
Here is the publicity page:
http://www.hagen.com/uk/publicity/aq...nderwater.html
To save time, I'll just say that it's all true

Easy, quiet and effective. Clears the water of crap in no time! The two filter pads are a really useful feature, meaning you don't have to go through a mini-cycle every time you change the media. The clogging indicator is another good feature. The filter is very easy to take apart and clean, too; I rinse my filter pads every week in tank water because it's so simple. It's quieter than my air pump, and could even do the air pump's job (it has a venturi device which you can use for aeration). The
only disadvantage with this filter I've found is its size; it takes up quite bit of space in your aquarium. But with some clever placing of plants, it can hide away in the corner quite discreetly. overall, a really good filter and one I'd recommend to anyone who can't get aquaclears and biowheels in their country
