Currently, our Modpools are chlorine only. Saltwater is more corrosive in its nature, thus requiring a lot of R&D before we are comfortable rolling it out in a container pool.
We hope to have it available sometime in the future, but at present, we are not able to offer a saline filter option.
The best way to reduce the use of chlorine chemicals, though, is to add on the UV Sanitation and TruGuard Filtration into your Modpool.