We have a vacuum cleaner, Hoover TurboPower 5000 that is maybe 12 years old. Only one room with carpet that we use it on, 18' x 27', the master bedroom. Most of the floor is covered with a queen size bed, three dressers, my executive desk, a work table 24" x 12'. a couple of filing cabinets 4 book cases, etc. Not much carpet is really exposed to traffic, probably less than half.
I cleaned house yesterday and vacuumed this room using Carpet Fresh with vacuum booster and OxiClean dirt fighter. I shampoo this carpet about once a year, or when the spirit moves me.
This morning we bought a new vacuum. I unpacked it, set it up and read the manual. It is a Hoover WindTunnel 3 HIgh performance Bagless upright.
To try it out, I ran it over the carpet in our bedroom even though I had just vacuumed it yesterday. I emptied the canister into a plastic pail and weighed it on the medical scales we have. I took out over five pounds of dirt from a carpet that had just been cleaned. Five Pounds!