I have no personal experience with that exact application however,replacement of sand with Filter Ag in existing installations may increases filter capacity 100% or more. (Caution should be taken upon start-up that the lightweight
Filter-Ag is not washed to drain.)
Another and maybe more applicable solution would be to replace the sand with a multi-media bed. That is a media that has 2 or more layers of media. Some use sand and anthracite. Some use sand, anthracite and garnet. I have had excellent experience with the latter in swimming pool applications. Multi-media beds, particularly the 3 layer beds, do a far better job of filtration down to as low as 10 micron particle sizes.
Gary Schreiber, CWS VI
The Purolite Co.