The Pentair brochure seems a little misleading to me. I do see that it says a cartridge type filter, and in this case the "cartridge" is a removable D.E. membrane, but generally speaking a cartridge filter is a paper or cloth filter element. That is what I was trying to clarify. I very strongly suspect you'll NEVER pay for the difference in price of that filter and a good sand filter through the savings on electrical power.