Cecil, I'd beg to differ on the MB3 not clogging. Even the product info comments that only the outside is self cleaning and the inside is a "protected" area as quoted from Watertek....WMT�s WaterTek MB3 polyethylene media is robust, durable and bacteria friendly; With a specific density slightly below 1.0, the media fluidizes easily with air. MB3 delivers a self cleaning outer surface with plenty of protected inner surface area.....from expeience, that bacteria slime will completely encapsulate areas.
I can't find the more detailed information on Pentair's LifeGard site on the sand media design, but here is some basic info......
http://www.petco.com/product/8167/Rainbow-Lifegard-Replacement-Media-for-Fluidized-Bed-Filters.aspx
