The Honeywell HA150 circulates a full room's air approximately 5 times in one hour. This includes all particles 0.3 micron size or larger. Actual performance will vary based on the size of the room.
Depends on tank size. if it's very small and easy to clean-you can just pump in air with an air stone or ornament, but if it's 5 gallons or more and you plan to add more fish, a filter will keep it...