Drop in Salt Level & Calcium Hardness

[Kit]

I recently reconnected the SWCG after a 6-month winter layup. Ordinarily the salt level would be about 2,400 ppm in the spring. (I try to keep a target level of 3,000 ppm). However, this time the salt level dropped to 300 ppm over the same time period.
On another (possibly related) note, during the past several month the calcium hardness seems to lose about 50 ppm weekly.
Those 2 things seem to suggest that I am losing water. For the sake of information, my in-ground 2,500-gallon spa has an auto cover & an auto fill. Although my water bill does not seem to have appreciably changed, I will check the water consumption over the winter compared to the same time period last year.
If anyone has any thoughts regarding the changes in salt & calcium hardness levels. I would really appreciate your input. Thank you so much.

 

[Texas Splash]

I think you ID'd the biggest concern being potential water consumption over the winter. The autofill would certainly mask the symptom. If you are forced to investigate plumbing more, the article below is a good start.

One last thought, your signature doesn't show how you test, but be sure your testing is accurate. Fresh reagents, proper test kit (TF-100 or Taylor K-2006C).

Leak Detection

A number of things can cause leaks in your pool. You can learn tricks for leak detection and how to pinpoint where your pool is losing water.

www.troublefreepool.com

 

[Kit]

I think you ID'd the biggest concern being potential water consumption over the winter. The autofill would certainly mask the symptom. If you are forced to investigate plumbing more, the article below is a good start.

One last thought, your signature doesn't show how you test, but be sure your testing is accurate. Fresh reagents, proper test kit (TF-100 or Taylor K-2006C).

Leak Detection

A number of things can cause leaks in your pool. You can learn tricks for leak detection and how to pinpoint where your pool is losing water.

www.troublefreepool.com

Thank you for the info. I test with both the Taylor salt kit, as well as the readout on the Pentair EasyTouch control panel.

 

[Texas Splash]

as well as the readout on the Pentair EasyTouch control panel.

I'm not familiar with that one. Perhaps @Jimrahbe can give me some insight and/or confirm if there are variances in the results you should be aware of

 

[Jimrahbe]

I test with both the Taylor salt kit, as well as the readout on the Pentair EasyTouch control panel.

Kit,

As long as both your test and the reported salt level from the SWCG are reasonably close, then I would trust it.. If the cell and your test are far apart, I would always go the the tested salt level vs. the reported salt level from the SWCG, which can be way off..

As you suspect, it sounds to me like your Spa has a good sized leak.. You should shut of the autofill and see how much it leaks each day.

The water has to go somewhere.. Got any wet spots in the yard???

Thanks,

Jim R.

 

[Kit]

Kit,

As long as both your test and the reported salt level from the SWCG are reasonably close, then I would trust it.. If the cell and your test are far apart, I would always go the the tested salt level vs. the reported salt level from the SWCG, which can be way off..

As you suspect, it sounds to me like your Spa has a good sized leak.. You should shut of the autofill and see how much it leaks each day.

The water has to go somewhere.. Got any wet spots in the yard???

Thanks,

Jim R.

Jim,

I turned off the auto fill & set up the "bucket test" that Texas Splash suggested. I will get a better idea tomorrow. No surface wet spots.
In the upcoming months I plan to have the spa re-plastered. The white surface has become quite discolored over the past 9 years. Also, there is a considerable amount of rust around the small (return?) port. I assume that there must be some ferrous material behind the plaster & that water is leaking from the spa, thus, causing the rust. Also, there are a few hairline cracks around the main drains. So re-plastering should eliminate any leaks from the spa itself.

 

[Jimrahbe]

Kit,

I'm not saying it is not the plaster, but pool/spa leaks are almost never caused by plaster issues...

The best test is to just let it leak, until it stops.. Obviously it stops leaking, when the water gets just below the leak.

Most likely, in order..

1. The skimmer
2. Returns pipes
3. Lights
4. Drain

Thanks,

Jim R.

 

[Kit]

Thanks, Jim. I just need to start eliminating possible leak sources. My water consumption indicates that (if indeed there is a leak) it is not major. I'll see what the bucket test indicates tomorrow. Thank you for your input.

 

[Kit]

Just wanted to post the results of the 24-hour "bucket test". (Actually I used 2 buckets). The water level in the spa remained constant. However, the water level in the buckets dropped by 1/2". So, if this test is valid, there is either no leakage or the leakage is relatively small.

I am trying to think of other factors to explain the loss of salt & calcium. I know that I had cleaned the filters a couple of times (which required draining the filter tank). But that itself represents a minor loss of water.

 

[Kit]

This is a follow-up to original post. In addition to the bucket test (as mentioned above), I also shut off the auto fill & the pump for 24 hours. The water level fell about 3/6" to 1/4" (with the cover in place). According to the guy who will be re-plastering my spa, that amount of water loss is within the "normal" range.

To add to the possibility of a leak, a couple of days ago I noticed that the chlorine level was zero (which surprised me). Based on the pool math calculator, I added 26 oz. of liquid chlorine to raise the level to about 3-4ppm. The next day the chlorine level was again zero. So I added about 55 oz. of chlorine to get a benchmark reading. After the chlorine circulated for a few hours, the level read 6.5ppm. After 24 hours, the chlorine level was again zero. Correct me if I am wrong, but this again seems to suggest a leak.

Regardless if he is correct or not, when the guy re-plasters the spa, he will also re-seal the light & pressure test the PVC pipes. In the meantime, I just want to be sure that there is not some other factor causing the loss of chlorine. BTW, I might add that the air temperature here has been in the 90Fs for the past 2 weeks. If anyone has any additional information that might explain this issue, I would truly appreciate it. In the meantime, I plan to turn off the auto-fill, but let the pump run continuously, for about 3 days to note the fall in the water level.

As usual, thank you all for your help.

Kit