Thanks to each of you for your help. I found one site that sells the "conversion kit with replacement filters" for $720. I also found Sta-Rite system with the following for $580:

Sta-Rite System3 450sqft
Starter Package Flow Block and 3 Cartridges
The Retrofit Kit Contains:
One plastic manifold that installs in seconds and can be easily removed/reinstalled when cleaning out the filter vessel.
Three cartridges with the same square footage of media as the original OEM filter cartridges.
Replace cartridges are lower cost and east to use.



Can anyone tell me if the Sta-Rite system is for the same capacity as I currently have (13,000 gal pool plus spa)? The replacement cost on the filters on this site is $281 - and I've payed as much as $377 per filter in the past! If the Sta-rite system works - I'm thinking of going with it (and seeing if there are cheaper options).

Thanks again!