Hi Louse,
When we were there over Christmas there was a barrier between the salt water pool & Poseidon. It looked temporary to me but not sure. It made the walk to the beach bar much farther so we jut jumped on a cart. (we became lazy) They will probably have signage on the path to the salt water pool.
The Helios schedule is not yet “regular” nor it the “offerings; (Sometimes just a la carte sometimes some tasting stations) so I wouldn’t depend on that for a late dinner. Maybe the beach bar? We really enjoyed lunch at the beach bar one day.