Posted: Sat Jan 31, 2009 4:46 pm
I would not go for a Fluval 4+ despite owning one myself. Like Meg I used a Fluval 4 because I had one spare when I rescued Squirtle, and when it packed up whilst I was on holiday my friend quickly replaced it with a new 4+.
Whilst flow rates are important, there are occasions when you need to consider a little more than flow rate. The Fluval 4+ is one of those cases (as are probably most other internal filters).
On paper it pumps more with the media in place than a Fluval 405, but Hagen only rate it for about half the aquarium capacity.
There are two reasons.
Firstly the foam is small, meaning biological area is small, it may blast the water around quickly, but it is blasting it through very little filtration.
Secondly the foam is small, meaing it clogs quickly. As it starts to clog, the flow rate plummets dramatically, leaving you with a lot, lot, lot less than 1000 l/h. This means you need to clean it out more often.
Also you have no flexibility with media, there are fine filter pads, but if you put one in it will clog even quicker. There are carbon pads, but they are minute and very expensive compared to what you could put in a canister filter.
My advice is to spend the extra money on a canister. You will not regret it.