If you're talking about saltwater as in a SWCG then there's no difference in the effects on EPDM material. The SWCG makes the same chlorine that pouring bleach or any other form of chlorine is. So that will make no difference.
As for the effects of chlorinated water on EPDM, It's rated as a 1 (Good) for Sodium Hypochlorite and a 2 (Fair) for Hypochlorous acid and Chlorinated water. I'd say that in the concentrations you use in a pool, it'll be fine.
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