Salt levels in pool with refil from salt ion exchange water softener

[yzf600]

I recently purchased a SWG for my pool. I bought enough salt at the store to bring the levels up to 3500ppm. I now just installed a water softener that is the source of the autofill for the pool. Now that it's 2 weeks since I installed the softener, the SWG (Intellichlor IC40) is showing the salt levels are high.

I did some research and found that on average for my area (17 grains of hardness), the softener puts in 100 milligrams of sodium/quart of water to soften it. Another site says that 1 ppm is about 1 milligram/liter. Since 1 liter is barely more than a 1 quart, 1 ppm ~= milligram/quart. I estimate my pool looses about 8 gallons a day (450sq ft in Phoenix). 8 * 4 = 24 quarts * 100 milligram/quart = 240 ppm added to the pool per day. So if my pool starts out at 3500 ppm, after about 10 days it should be close to 6000ppm, which is the limit I've read in other threads that one does not want the pool to get to.

Is my conversion right? I would have figured that if this "salt level creep" was this fast, others would be discussing it here. The only metal I have in my pool is the light.

I'm glad to keep the CH in check for my pool now, but I may have traded one problem for another. It's not going to be easy to run a pipe from the front of the house all the way back to the pool autofill to bypass the softener.

 

[Killer95Stang]

Do you have automation. If so, you can see what the Pentair Automation is seeing in diagnostics. Otherwise, get some salt strips or better yet the drop test for salt. Then you can compare your formula with your tested results. From looking at your calcs, it appears you are wrong. You never took into account that you are adding to a 15K gallon pool.

 

[yzf600]

Current test strips say levels are somewhere around 4000ppm. My automation is a home grown, DIY system that can't communicate with the IC40. Maybe one day someone will decode the protocol and I can query the salt levels.

Ah yes. While the softener is adding 2400 milligrams of salt per day (24 quarts * 100milligrams/quart), that needs to be divided by the volume of the pool (15k*4) to see the final milligrams/quart added per day. 60k quarts / 2400 milligrams = 25 mg/qt =~ 25 ppm. This gives 100 days to rise from 3500 to 6000.

That is still not right. I went to the pool calculator and calculated it would take 314 lbs (almost 8 bags) of salt to rise from 3500 to 6000 ppm. The softener tells me 8 bags of salt will last for 120 days, and that is for the whole house. The softener also says we use about 100Gallons/day, so the pool is only 8% of the total. I'm sure the softener does not work at 100% efficiency (meaning a lot of the salt goes straight down the drain port).

My attempt to use math and estimation is failing me. Perhaps it's time to break down and buy a drop test for salt. That way I could test week/week to see what the rise in level is.