Totally agree extra filtration is good

also remember that manufactures statistics are a little over rated.
I have never been a fan of manufactures recommendations that a filter is suitable for a specific volume tank I have always preferred to work out my tanks needs by volume of water turned over per hour.
As I understand from what I have read here in the past most manufactures water turn over claims, work on water flow per hour and is tested without any media in the filter?
So for example a claim from the manufactures claiming 1000 litres an hour turn over will be a lot different when set up on your tank with media in it and of course as time goes by and the filter picks up rubbish from your tank the rate will reduce even more.
For the life of me I cannot remember what you should be looking for as far as water turn over per hour I.E your tanks volume 60 litres per hour some say X2 = 120 litres per hour some say X10 =600 litres an hour which rings a bell and what I have set my tank up to do, the more the merrier in my humble opinion of course you get to the point were to much can be a waste of money as far as running costs are concerned and of course your budget for the filter is another factor.
Hopefully some one will post what sort of turn over you should be looking for of course it also depends on what sort of fish and how many you are keeping so if you posted your stocking that would help.
I hope this helps regards onebto