I have a Magnum HOT Pro on my 55 gallon, along with an EMP 400. I have also had another MAG HOT which was given to me before. I think these filters are great for having the options of varied filtration. You can use the media basket (with filter sleeve around it) as your all-around filtration, either with additional mechanical media or carbon as needed. You can trasform it into a polishing filter by removing the basket and using the micron filter (which only lasts about a week before clogging in my tank). You can also use the gravel vacuum attachment (if you have this part) to clean your tank thoroughly, while being able to take your time with it. The filter basket can be filled with bio-media (which I have done successfully), but it isn't very large and is better used for mechanical/supplemental filtration, IMO. As long as you keep up with basic cleaning, your tank should be fairly clean and well-filtered with those two filters, even though I really don't like the Penguin filters.