Confused about Salt Residual

[rcy]

And all this time, I though the salt gnomes were stealing it during the night.

Seriously, though, if I understand this correctly - if water only evaporated from my pool (no splash out or backwashing etc.), and the salt gets left behind, then my salt concentration will be stronger (less water right). When I add fresh water from the garden hose, it's not making the salt concentration weaker than before the water evaporated, just reducing the greater concentration (because of less water) to the level it was before the water evaporated.

However, in real life, where water is lost through splash out and backwashing as well as evaporation, when I add fresh water from the hose to top up my pool, the concentration of salt will get weaker, since I lost salt and water when I backwashed/exited the pool with my wet thong and am replacing that lost water with fresh water only, no salt. Hence, once or twice a season, I might have to add a bag of salt to the pool.

 

[JasonLion]

Yes, that is a good explanation of what happens.

 

[alanpaul]

Thanks for the great explanations.
I've returned here after 2 years, and understand that the loss of salt was truly due to backwashing the DE filter, and copious amounts of rain.
[And actually, we don't drain the pool. Water just disappears when the water level gets above a particular horizontal grout line about 2" below the concrete deck. A little scary, hunh? We've been here 7 years and have never found any overflow or outlet for excess pool water....]