One of the major benefits listed for adding salt to a pool is that is makes the water feel soft. I have a water softener and understand the principles that it operates by. From what I've read, a typical water softener will not normally need to exchange more than about 300 mg/l of sodium ions to displace the calcium and magnesium ions unless the water is exceptionally hard. At this point you effectively have "salt water" at a concentration level of 300 ppm.
Here's the question. If salt is added to water that has not already been softened, what is the relationship between the salt concentration in the water and the amount of calcium/magnesium that is displaced. For example, If I added 1000 ppm of salt to water that had 300 ppm of calcium/magnesium, would the salt completely displace all of the calcium/magnesium? Not that it would be practical, but could you raise water to a high salt concentration, displace the calcium/magnesium, and then (somehow) filter the salt back down to a low level and effectively end up with "softened water"?
Disregarding the benefits of salt in the water in regards to the burning of the eyes and nose, would using softened provide the same essential feel to the skin and hair as salting the water? What about using softened water and then adding lower levels of salt to it (500 - 1000 ppm)? I guess I'm trying to determine if we can enjoy many of the benefits of salt water while reducing some of the potential for corrosion issues.