Answer to the question about above ground pools and tracks, I disagree that you're only dealing with 1000 - 1500 ppm of salt. While this is true with the pool water, splash out water that ends up in the tracks will eventually evaporate, increasing the salinity level as the water evaporates. Realistically, your salt concentration of the water in the tracks can increase way past the 35000 ppm of ocean water.
I recommend that you occasionally wash down the sides of your pool or you will see corrosion over time. Regular rain fall or your sprinkler system hitting the outer pool walls will keep the salt concentration down.
I was thinking that sealing the bottom of the wall where it fits into the track with some Clear Silcone caulk would also be a good "ounce of prevention". It would keep the salt water penetration to a minimum.

.