Hey guys, I have a 20g as you can see in my signature. I have 2 rainbow sharks that are going to outgrow this tank and will be upgrading to a larger tank at some point. My concern is that my hob filters will not be enough for a tank of about 55 gallons. So, obviously I don't want to spend a ton of money on a new filter, but also don't want to get a used one either. Never know what's been in someone else's tank. Which canister filter is going to be relatively inexpensive but also do a good job filtering? Also, is the media that comes with these sufficient? I saw a video of a guy who replaced the included media with foam and other types of bio media. Thanks for your input!