if u've got room, you could get a hang on the back filter such as an aquaclear, they're very good and you don't need to take up too much tank space that way...cos it is only a 65L tank.
aquaclear 30 or 50 should be fine... or if you wanted to spend the money you could get an eheim cannister filter, 2213, that would be good too. retail they're about $160-180, but im sure you could get a good deal on TradeMe or something......