Rising Salt Level

[bdavis466]

I seem to have an unusual situation where my salt level is rising. The pool was completed in March of this year.

I have a SWG pool and the salt was added 30 days after plaster application (StoneScapes) to 3200 ppm (700 pounds) which was confirmed by the salt cell (Pentair IC60) and Taylor 1766 test kit. I have seen a steady rise in the salt level which is now 4300 ppm (confirmed from salt cell and 1766).

I understand that acid additions add salt as a byproduct (I add roughly 1 gallon per week), liquid chlorine's net product is salt (I've added no more than 3 gallons total in this time span), and the SWG's chlorine production doesn't significantly impact the salt level either way. Is it possible that the acid additions alone have added nearly 300 pounds of salt (3200-4300 per Pool Math)?

Most people I have talked to in my area (with the same fill water) seem to indicate the opposite problem (salt level decreasing) which is what I would expect and makes my situation more questionable.

Regardless, here are the numbers:

pH - 7.7
FC - 8
CC - 0
TA - 60
CH - 650
CYA - 80
Salt - 4300
Temp - 74
CSI Range - -0.1 to -0.3

I have never had any scale in the salt cell as I have maintained a negative CSI from the day I installed the cell, so I don't think the reading is an error. All salt tests have read within 100-200 of the reading I get from the IC60. I am also aware that the cells do not actually measure the salt level and they do not correct for temperature variations.

The fill water:

pH - 8
TA - 120
CH - 125
Salt - 40 to 60 ppm (best I could determine with the Taylor test and a larger volume of water) the was later confirmed by the Water Company's quality report (indicated 50 ppm).

Another thought, could high CH levels skew the test and the cell's reading?

 

[Texas Splash]

Giving this a bump for visibility since there's been no reply. I don't suspect the raise in your salt readings has anything to do with the CH or acid treatments each week. Typically we would look for salt increase to come from either an excessive percentage setting or lengthy run time of SWG. Your equipment is new correct? So I wouldn't expect there to be an equipment issue, but you never know. If it is still new, I would think it's under warranty to where you can ask the builder or call Pentair directly perhaps? In any case, I hope this "bump" helps get other replies for you. Best of luck, and have a nice day.

 

[pabeader]

How do you fill your pool? Water from house? Just for fun, check the salt level in your fill water...

 

[PoolChickTX]

How do you fill your pool? Water from house? Just for fun, check the salt level in your fill water...

We have similar equipment and have a nozzle to turn. It was told that we should keep the levels (measure 1/2 way from skimmer things. (Sorry I am new). I've read as well that the three most common reasons for getting air in your pump are above and I'll let someone else answer the other two.
I actually was curious and tested our water with my kit. Not for fun but I wanted to check Chlorine from our tap water. I hope this helps.

Sent from my XT1096 using Tapatalk

 

[bdavis466]

Giving this a bump for visibility since there's been no reply. I don't suspect the raise in your salt readings has anything to do with the CH or acid treatments each week. Typically we would look for salt increase to come from either an excessive percentage setting or lengthy run time of SWG. Your equipment is new correct? So I wouldn't expect there to be an equipment issue, but you never know. If it is still new, I would think it's under warranty to where you can ask the builder or call Pentair directly perhaps? In any case, I hope this "bump" helps get other replies for you. Best of luck, and have a nice day.

Thanks...High percentage and run times on the SWG create salt?

How do you fill your pool? Water from house? Just for fun, check the salt level in your fill water...

The fill water numbers were located at the bottom of my post. 40-60 ppm of salt

 

[PoolChickTX]

Yes! Use that warranty... Unfortunately we moved into a resale and all of our equipment has expired.

Sent from my XT1096 using Tapatalk

 

[pabeader]

My bad. So with that, every gallon of water you put in you are adding 50 ppm salt. Only takes 22 gallons or so to add up to 1100 ppm salt, right? Or am I doing something wrong there???

 

[Texas Splash]

High percentage and run times on the SWG create salt?

Bwaahaahaa! I guess you can tell it was still too early for me this morning.

Here is a quote from another expert regarding the correlation between salt, acid, and chlorine:

More specifically, it lowers the pH and TA and increases chloride (salt). Generally speaking, the amount of salt buildup from Muriatic Acid is far smaller than than from chlorine, but even that is a rather slow buildup since salt is rather innocuous except at much higher levels. With bleach or chlorinating liquid, at 2 ppm FC per day chlorine usage the salt increases by around 100 ppm per month if there is no water dilution.

 

[chawkins99]

My bad. So with that, every gallon of water you put in you are adding 50 ppm salt. Only takes 22 gallons or so to add up to 1100 ppm salt, right? Or am I doing something wrong there???

22 gallons of 50ppm is still 50ppm. Adding 100 gallons of 50ppm to a pool at 4000ppm will actually reduce the concentration in the pool, not increase it.

The only ways for a pool to increase from 3200ppm to 4000+ppm is either the addition of raw salt (in some form) or adding water at considerably MORE than 4000ppm (sea water maybe).


ETA: I suspect testing errors.

 

[pabeader]

Too early, and too much candy for me!!!

 

[Texas Splash]

A few other discussions related to your situation that may help:
Salt level keeps rising
Salt level rising?
Salt level keeps increasing

 

[bdavis466]

22 gallons of 50ppm is still 50ppm. Adding 100 gallons of 50ppm to a pool at 4000ppm will actually reduce the concentration in the pool, not increase it.

The only ways for a pool to increase from 3200ppm to 4000+ppm is either the addition of raw salt (in some form) or adding water at considerably MORE than 4000ppm (sea water maybe).


ETA: I suspect testing errors.

Adding water with any amount of salt in it will increase the salinity concentration regardless of the salt level of the pool since salt (as well as most other disolved solids) does not evaporate.

The only time your statement would be true is when water has been drained from the pool and then replaced with fill water of a lower salt concentration.

Testing error would imply that the swg and my drop test are both exactly wrong by the same amount ....hard to fathom since each determines salt levels by a completely different means

 

[bdavis466]

My bad. So with that, every gallon of water you put in you are adding 50 ppm salt. Only takes 22 gallons or so to add up to 1100 ppm salt, right? Or am I doing something wrong there???

Each gallon at 50 ppm in 33,000 gallons adds 0.0015 ppm of salt, 22 gallons is 0.033 ppm.

 

[pabeader]

I knew there was something I was missing...

 

[chawkins99]

Adding water with any amount of salt in it will increase the salinity concentration regardless of the salt level of the pool since salt (as well as most other disolved solids) does not evaporate.

Not so. Adding water with a lower concentration compared to the current will dilute it. The total QUANTITY of salt will increase, but the CONCENTRATION (ppm) will decrease.

Taking your argument to the other extreme. When water evaporates, the concentration will stay constant. What actually occurs is the Quantity of salt remains constant but the quantity of water reduces, thereby increasing the salt CONCENTRATION.

 

[bdavis466]

That is correct as far as evaporation is concerned, but water evaporating with no salt in it and being replaced by water with salt in it will increase the salt levels within the pool. This is the exact same way that calcium levels rise due to water evaporation when fill water contains any amount of calcium.

Water lost due to splash out, draining and/or an overflow line is a different story. The water lost contains more salt and calcium than what it is replaced with and would then decrease the salt and calcium levels by dilution.

 

[chawkins99]

OK. One more time...

Let's start with a pool containing 20,000 gallons at 3,000ppm salt.

We drain 10,000 gallons (which includes 50% of the salt). The CONCENTRATION is STILL at 3,000ppm.

We now add 10,000 gallons of fresh water (zero salt). We now have 20,000 gallons but now at 1,500ppm because now we have twice as much water for the same amount of salt.

Now, what you're saying is that if we add 10,000 gallons of water with a trace amount of salt (let's say 1ppm), then the pool will now be at 3,001ppm.

What do I have wrong?

 

[bdavis466]

OK. One more time...

Let's start with a pool containing 20,000 gallons at 3,000ppm salt.

We drain 10,000 gallons (which includes 50% of the salt). The CONCENTRATION is STILL at 3,000ppm.

We now add 10,000 gallons of fresh water (zero salt). We now have 20,000 gallons but now at 1,500ppm because now we have twice as much water for the same amount of salt.

Correct

Now, what you're saying is that if we add 10,000 gallons of water with a trace amount of salt (let's say 1ppm), then the pool will now be at 3,001ppm.

What do I have wrong?

The pool would be roughly 1501. You are talking about DRAINING water and refilling, I am talking about EVAPORATION and refilling. Evaporation leaves everything behind which is why my salt and calcium levels are rising

 

[pabeader]

You said drain. Unless I missed it, nobody else said drain. (except bdavis in a side note.)
Evap causes the concentration to increase. So if you evap 1/2 the pool you get 6000 ppm. If you fill with water that has salt in it you will not end up back at 3000ppm but some amount higher than that.

 

[chawkins99]

Correct



The pool would be roughly 1501. You are talking about DRAINING water and refilling, I am talking about EVAPORATION and refilling. Evaporation leaves everything behind which is why my salt and calcium levels are rising

Correct. The pool would be around 1501ppm.

BUT... before adding the 10,000 gallons at 1ppm, the pool contained 10,000 gallons at 3,000ppm. Where did the other 1499ppm go?

Regardless. As you indicated in your original post, the only way to go from 3200ppm to 4300ppm is by adding 300lbs of salt which could not possibly have come from a couple of gallons of acid (or anything).

So, maybe your original reading of 3200 was before the salt had fully dissolved although salt will usually dissolve within a couple of hours (24 hours max).

I will admit that when I converted to SWG, I was using the salt test strips incorrectly resulting in a false low reading so I added more salt before realizing the error. I had to do a 40% drain/refill to fix it.

- - - Updated - - -

You said drain. Unless I missed it, nobody else said drain. (except bdavis in a side note.)
Evap causes the concentration to increase. So if you evap 1/2 the pool you get 6000 ppm. If you fill with water that has salt in it you will not end up back at 3000ppm but some amount higher than that.

Yes, I meant to say drain to try and explain the concept. It wasn't a faux-pas.