listen man youve got an aqua clear and a whisper and your buying a canister and now you want a e400? I hope you bought stock petsmart cause they are gunna have field day when you come in. Why not stick to one kind and then you know how it works and how to fix it and how to clean it, instead of having every brand in the industry to worry about. And you could go and buy bulk of what you need and save versus buying several of different kinds. On a big water change day you might have to go to several stores just to find all the brands of filters you need. Not to mention your gunna run out of room and your tanks gunna look more like a science expiriment than a turtle tank.
I know your new and theres alot of options but my advice would be try to keep it simple, or your gunna be chasing your tail all the time.
btw your turtle looks great and good luck