Check the salinity of the water coming out of your softener if you haven’t already. If you can catch it right after a regen cycle that will tell you what the max salinity of you auto fill line would be. Towards the end of the softener cycle (just before regen), the salinity should be close to whatever the supply line salinity is.
I did all that testing last month (remember the rain water experiment?). In addition to the softener, I have a whole-house filter, too. Both the test of the city water and the test of the water after the filter/softener combo turned the K-1766 solution bright after just one drop. So I take that to mean 100 or less, right? I didn't test right after the regen.
Are you guys saying that the replacement water would have more affect on salinity creep than how chlorine and MA affect accumulation of salinity?
Either way, this is somewhat academic. I've figured out how to top off my pool with the absolute lowest CH/salt water I can get at my house. So the creep is going to be the creep. But I put some effort into minimizing that, so time will tell if that effort was well spent.
Hypothetically, even if one could successfully put off a water replacement for CH/salt reasons indefinitely, wouldn't it be prudent to do a replacement periodically anyway, just to clear out all the accumulated "stuff" we're not measuring for? My plaster installer swore by that, alluding he does a water change every year or so (well, partial change), regardless of CH or salt.
I wouldn't do that, but I would think a 3 or 4 or 5 year cycle might be healthy, maybe a half at a time, to keep some weight on the ever-aging plaster.
Or do you all just let it go until the CH is 1000+ (or more), regardless of how many years that might take?
--edit--
Sorry OP, I've completely hijacked your thread. I hope this conversation is at least somewhat useful...
