DE filters use a coarse woven nylon material as the supporting surface for the DE to land on. DE will not embed easily into that material. Cartridge filter elements use a spun polypropylene material for the filter surface (almost feel like paper). DE can become entrained into the PP material which makes it much harder to remove. Over time, the DE will simply plug up the cartridge filter element.
Jacks Filter Fiber Stuff is an organic fiber material made from lignin. It acts as a high surface area material which helps to absorb and hold on to fine particulates. Chlorine only oxidizes it very slowly. If you rinse the cartridges frequently, then the FF Stuff will come off. If you don’t rinse frequently and leave the FF Stuff on too long, it becomes “gummy” and glue-like and will be next to impossible to clean off.
In general, filter aids really don’t do much good but can cause lots of problems. The limited amount of clarity improvement you might see, mostly at night, isn’t worth the hassle of dealing with all the extra cleaning.