I have always wondered about getting an exerternal filter but i know nothing about it. I was put off getting one last time i went in my LFS when the guy went on and on and on... poor little me standing looking very confused and he was still going on and on... I know a fair amount about internal filters having always had them. But could some one tell me a little more about external ones. (in a slightly simple female way!) (remember simple ) I have 125L at the moment and i was hoping to upgrade to a 200L at some point so would deffently look at getting one for that. Thank you for any help now and for being patient with me.