Aquarium Filters?

dragonbait0126

I have a 55 gallon aquarium with 1 giant goldfish (that I won from the state fair!) and 5 cory cat fish. I'm looking for a new filter and would love an underwater one to help pull debris from the gravel in between cleanings. Anyone have an underwater system they would reccomend? I've also been looking at canister filters so any thoughts on those are welcome as well. I currently have a 100g H.O.B. filter that has the carbon filters you have to change at least once per month if not more often. Although it's a great filter, it just isn't powerful enough for all the bottom debris. I'm considering leaving it in place and just adding an underwater filter to my set up. It also needs to be one that works well with smaller fish. I've had goldfish for over 15 years and I've decided that when this one dies, I'm getting away from them. I love them, I do, but, they are so dirty and produce so much waste it's insane. That and I'd like to have a community instead of 1 giant fish and a few bottom feeders.