Calcium Hardness JUMP, Lesson Learned; But why the rise in Salt? EXPERT HELP NEEDED.

[panamax53]

I have been a member for over a year and have been relying on testing w the Taylor K-2006 Salt Kit. I have been very confident in my testing accuracy, but screwed up in the following ways. I had recalled reading somewhere that once CYA is set, salt is set and calcium is set the only way to change them would be to pump water out of the pool.

I last checked salt on 28 December 2016 it was 4200 ppm. It jumped to 5200 ppm by 21 April 2017 without any salt additions.
I last checked CH on 16 December 2016 it was 375 ppm. It jumped to somewhere between 550 ppm and 600 ppm by 21 April.
I questioned my readings. I went to the chain pool store. They confirmed I was higher than 500 but could not validate the number.
They agreed with my salt reading of 5200.

My local water is 50 ppm CH.

I check CL and pH two to three times weekly. TA and CYA monthly. I

I slammed the pool to 32 ppm at the end of December.

A chlorine reducer purchased at the pool store was used to bring the chlorine down after slamming. I had some low pH so I needed 3 boxes of Borax to bring things back up to normal.
After that, I have kept the pool looking beautiful and in TFP specs w regard to FC, TA, pH and CYA.

Only city water at 50 ppm CH has been added. Baking Soda used to maintain TA around 60 - 65.. Stabilizer to get CYA to 75-80. Daily acid from a stenner pump and the swcg to produce chlorine.

I suppose the answer for the jump in CH is due to the occasional filling of an inch or two of the city water. But, a 35% increase???

What explains the rise in NaCL? No salt was added! What could have happened?

There were two indicators: My cell plates were accumulating calcium deposits more rapidly and my daily dose of muriatic acid went from 6 oz to 10 oz to maintain a pH of 7.7 over the past 3 months.


Hope this lays out the issues clearly.

Thank you for your analysis.

 

[atttech-2]

Some of the salt likely came from liquid chlorine adds over the winter. As for the CH is your pool new? My new pool went from 350 CH to 600 in about 10 months I was keeping my pH around 7.6 most of that time and my fill water is about like yours I don't think I had near the evaporation that would have been needed to double CH. I don't know if the rise was due to low pH or new plaster or both but what ever the cause it seems to have leveled off I and not increasing near like I was in fact I it went down 200ppm from rain over the winter.

 

[bdavis466]

Nearly every chemical you add to your pool contains salt or more accurately, chloride. Acid has insanely high amounts of chloride and if added frequently will certainly show up as a rise in salt levels in no time at all.

One gallon of full strength acid in your pool is the equivalent to adding 5 lbs of salt and will equate to a 32 ppm increase when testing.

 

[panamax53]

Sir,
Your responses have been most helpful in understanding the chemical reactions going on here. Thanks, once again! No one else has been able to provide that information. Each 40 lb bag of pool salt raises my ppm by 300 ppm.

Adding 8 oz. of acid a day comes to one gallon every 16 days and as you say equals 5 lbs of salt. Over the 4 month period it would come to about 8 gallons of acid which would create 40 lbs of salt and raise NaCl 300 ppm by my calculation or 256 by yours. That gets us between 4456 ppm and 4500 ppm of NaCl. The other 700 ppm came from where? The occasional liquid chlorine additons along with my SWCG?

So, I found the need to search out a more efficient method of adding acid. You may recall I installed a Stenner pump and 15 gal tank to take care of things January of 2016. I dilute 50/50. My SWCG required me to add about 6 oz of acid a day in the first months of pool life. Now it is asking for 10 oz a day to stay in the 7.7 range. Not sure I understand that, but that is what it takes. I am fairly anal about testing pH and FC on a daily basis. I try to keep TA on the low end, about 60 and not over 70.
Another odd chemical reaction occurred today by adding 16 lbs of calcium plus. That was supposed to raise my calcium level by approximately 66 ppm from 300 to 366. My SWCG was supposed to produce 2 ppm chlorine today. Salt level is 3800 ppm. Ideal amt would be 4000 ppm for my Jandy Aquapure Ei. .My CYA is around 65 -70. My morning 8 am reading of FC was 6.5 . My 6pm reading was 3, I double checked it! No one swam in the pool. Does the addition of 16 lbs of calcium plus cause a drop in FC?? I don't know what else could explain it. Yesterday my end of day FC reading was about what it was in the morning and it had been a hot sunny day.

 

[bdavis466]

Calcium chloride also adds salt (chloride). The calcium addition had nothing to do with FC consumption so you have something else going on there.

Most fill water sources contain salt. I know mine is anywhere between 60-100ppm. A 700ppm discrepancy between testing and calculations is probably within the margin of error since none of what we are doing is exactly precise.