The Fluval 205 is an excellent filter IMO. Much better than an internal.
1/ Increased turnover
2/ larger capacity for filter media
3/ More versatile, allows you to change filter media to suit your specific needs
4/ External meaning more spce in the tank
5/ No risk of detritus leaking back into tank when cleaning is required.
Its a great filter and you can pick one up pretty cheap from one of the large chain stores.
