I'm gonna make a DIY sump.....I have a 55 gal and my sumps gonna be a 20 gal aquarium. I'm gonna use a HOB prefilter, and my question is.....does my submersible pump in my sump have to match the overflow coming out of my main tank? And if so, how do I know the rating for my prefilter? which pump would you recommend in the sump?