Leak in Saltwater Spa?

[Kit]

Before I contact my spa builder, I wanted to do a bit of sleuthing on my own to determine if I likely have a water leak in my in-ground saltwater spa (2,200 gal.). Since the spa was built & filled about 4 months ago, I have been adding about 10 lbs. of salt every 2 weeks to maintain a level of 3,200 ppm. It didn't occur to me until recently that I might have a underground water leak that triggered the autofill, thereby decreasing the salt level. Keep in mind that my wife & I use the spa once or twice weekly & there is no splash-out. Also, the spa has an auto cover that is in place except when the spa is being used. There are no visible leaks in any of the above-ground equipment or plumbing.

So for the past 2 days, I shut off the auto fill. The the pump runs 3 hours daily for general filtration & chlorine generation. After 48 hours, there has been no reduction is the water level in the spa. Thinking that the leak might only occur while the pump is running, I manually turned on the pump a couple of hours ago & will let is run continuously for at least 24 hours to see if the water level falls. Are there any other suggestions of things I might check to narrow the cause of the problem?

Thank you for any thoughts & suggestions you might have. I truly appreciate your expertise.

Kit

 

[Rossterman]

What test kit are you using to verify levels of salt? Strips arent very accurate and the sensors sometimes very 200~300ppm in a short span of time. My guess is if you use a good test kit (taylor k-1766 is what I use) you will find it's probably staying steady if you have ruled out leaks and shut off the autofill.

 

[Kit]

What test kit are you using to verify levels of salt? Strips arent very accurate and the sensors sometimes very 200~300ppm in a short span of time. My guess is if you use a good test kit (taylor k-1766 is what I use) you will find it's probably staying steady if you have ruled out leaks and shut off the autofill.

Thanks for the response. To verify the salt level, I am using the Taylor K-1766 kit, as well as the readout from the IntelliChlor SWG. Both verifications tend to be within 250ppm of each other. However, in the pas tfew months the Taylor kit occasionally recorded a level 400 - 600ppm greater than the SWG readout. Nevertheless, both indicate that the salt level has been dropping over a 2-week period.

As an update, after running the pump continuously at 2350 rpms for 24 hours (& with the autofill shut off), the water level in the spa has NOT fallen. I'm confused??

Kit

 

[Kit]

Calcium Chloride & Salt Level Mystery

Moderator comment: The threads were merged together

First, forgive me since I posted this inquiry several days ago in the "Everything Else" subforum. Since then I gathered some additional information which I think makes this the appropriate place for my question.

Since my new in-ground, 2,200 gallons SW spa was first filled last February, I have added about three 40-lb. bags of salt after I initially stabilized the salt level at 3,400 ppm. That's about 10 lbs. every 2 weeks. Also, every couple of weeks I seem to be adding about 26 oz. of calcium chloride. Thus, my assumption is that I am leaking water somewhere which is triggering the autofill; thereby, dropping the salt level. [Please keep in mind that the spa has an auto cover which is always used except when we are in the spa (about 1 hour every 3 days). Thus, there is virtually no water loss due to evaporation. Also, there is virtually no splash-out except for the water on our bodies when my wife & I exit the spa].

With no visible surface leaks in the plumbing, I turned off the autofill 4 days ago. For the past 48 hours I have been running the circulation pump continuously. Interestingly, there has been no appreciable decrease in the spa's water level. In fact, I turned on the water supply to the autofill a few minutes ago & no fresh water entered the spa.

Question: Without any indication of a leak somewhere, how can my salt level be falling? Thank you for any guidance you can offer.

Kit

 

[bobodaclown]

Re: Calcium Chloride & Salt Level Mystery

It can't be according to what you've posted. But if you're constantly adding salt and Calcium, what about CYA (stabilizer). Then you're loosing water. I see you have a cartridge filter so no back washing to loose water.
How are you testing? Post test numbers. Turn off auto fill for a week. Check water level post test numbers.

Do you have a bucket? You could also do a bucket test. It's easy. Pool School - Leak Detection

 

[basod]

Re: Calcium Chloride & Salt Level Mystery

Are you sure the spa is really 2200 gallons?
by my math:
7.48gal/cuft of water
your spa is 14'x11'x(un posted depth) = total cubic feet of pool
2200(assumed gallons)/7.48 = 294cuft

294ft^3/14ft/11ft = un posted depth of pool = 1.9ft

That's a shallow spa:tongue:

measure the real depth, even if variable and post back.
Could be the under estimated chemicals are dissolving in the under estimated water?

 

[JamesW]

Re: Calcium Chloride & Salt Level Mystery

How are you testing salt? Are you going by the reading in automation? Do you have the Taylor k-1766 salt test kit?

 

[Kit]

Re: Calcium Chloride & Salt Level Mystery

It can't be according to what you've posted. But if you're constantly adding salt and Calcium, what about CYA (stabilizer). Then you're loosing water. I see you have a cartridge filter so no back washing to loose water.
How are you testing? Post test numbers. Turn off auto fill for a week. Check water level post test numbers.

Do you have a bucket? You could also do a bucket test. It's easy. Pool School - Leak Detection

The info that I provided in my original post is indeed correct. And, yes, I am adding CYA as well. I spoke with my spa builder, as well as a reputable pool maintenance company, & they both are rather stumped.

For the salt level, I am using the readout from the IntelliChlor as well as the Taylor salt test kit. Since I purchased the Taylor kit recently, I only have a few comparative numbers.

Date IntelliChlor Readout Taylor Kit Results

June 6 3,300 ppm 4,000 ppm
June 9 3,200 ppm 3,400 ppm
June 14 3,000 ppm 3,400 ppm
June 20 3,050 ppm 2,800 ppm
June 30 2,650 ppm 2,600 ppm (added salt as a result of these numbers)
July 5 3,350 ppm 3,200 ppm
July 6 3,350 ppm 3,000 ppm

I turned off the auto fill on July 2. As of today, the water level has fallen about 1/4" at most. I will continue to monitor both the salt level as well as the water level on a daily basis. Also, I will do the bucket test.

Thank you for your help. I will keep you posted.

Kit

 

[JamesW]

Re: Calcium Chloride & Salt Level Mystery

Is there an overflow drain line?

Is this a swim spa with a big pump for the swim jet?

 

[Kit]

Re: Calcium Chloride & Salt Level Mystery

Are you sure the spa is really 2200 gallons?
by my math:
7.48gal/cuft of water
your spa is 14'x11'x(un posted depth) = total cubic feet of pool
2200(assumed gallons)/7.48 = 294cuft

294ft^3/14ft/11ft = un posted depth of pool = 1.9ft

That's a shallow spa:tongue:

measure the real depth, even if variable and post back.
Could be the under estimated chemicals are dissolving in the under estimated water?

The spa measures 11' X 14' X 3.3' (depth). These is also a perimeter bench, as well as 4 steps of various sizes. By subtracting the volume of the bench & the steps, the volume of the spa is approximately 334 cu. ft. (or 2,500 gals.). So, my original volume of 2,200 gals. (provided by the builder) was a bit low.

Kit

- - - Updated - - -

Is there an overflow drain line?

Is this a swim spa with a big pump for the swim jet?

James: No swim spa. The only overflow that I am aware of is in the vault for the auto cover. But the water level in the spa is below the vault so there is unlikely any water overflowing into the vault.

Kit

- - - Updated - - -

How are you testing salt? Are you going by the reading in automation? Do you have the Taylor k-1766 salt test kit?

James: I am using both the readout from the IntelliChlor, as well as the Taylor K-1766 test kit. Please see the results I posted in this thread. Thank you.

Kit

- - - Updated - - -

How are you testing salt? Are you going by the reading in automation? Do you have the Taylor k-1766 salt test kit?

James: I am using both the readout from the IntelliChlor, as well as the Taylor K-1766 test kit. Please see the results I posted in this thread. Thank you.

Kit

 

[JamesW]

Re: Calcium Chloride & Salt Level Mystery

Sometimes the design of the wall between the pool and cover vault is such that water will be lost when the pool is in use due to waves going over the wall.

If you're checking for water loss during periods of no pool use, then you won't catch that type of loss.

Your salt tests definitely seem to indicate water loss and refill.

How far is the pool water level below the top of the wall?

 

[Kit]

Re: Calcium Chloride & Salt Level Mystery

Sometimes the design of the wall between the pool and cover vault is such that water will be lost when the pool is in use due to waves going over the wall.

If you're checking for water loss during periods of no pool use, then you won't catch that type of loss.

Your salt tests definitely seem to indicate water loss and refill.

How far is the pool water level below the top of the wall?

James: The water level is 5 1/4" below the top of the coping along 3 sides of the spa. The water level is 2 1/4" below the coping along the edge of the cover vault. I suppose that it would be more likely for water to be lost into the cover vault. But I am doubtful since my wife & I merely sit & relax in the spa. So there is very little wave action that might spill over the coping into the vault.

For the past 6 days there has been no spa use, the auto fill has been turned off & the cover has been in place. In this 6-day period, the water level has dropped about 1/4" at most. I would have expected a much greater decrease if there was an underground leak somewhere. If the water level continues to be stable (with the auto fill off), I would expect my salt level, CH & CYA to be stable as well. Am I correct, therefore, in assuming that if that is the case then my continual addition of salt, calcium chloride & CYA in the past would have been due to splash-out (which I find to be improbable)? This is perplexing.

James, I want to thank you for taking the time to help me troubleshoot this. It is truly appreciated!

Kit

 

[JamesW]

Re: Calcium Chloride & Salt Level Mystery

Your salt tests seem pretty reliable and consistent other than that first Taylor salt reading.

It wouldn’t take much wave action to cause loss over the vault wall. So, that’s a possibility.

A plumbing leak is possible. If you have a multi speed or variable speed pump, you might only lose water when the pump is at higher speeds.

I would say just keep monitoring and keeping good notes to see if there is anything that indicates what’s going on.

 

[Kit]

Re: Calcium Chloride & Salt Level Mystery

Thanks, James. With the auto fill off, I will continue to check the water level daily for another week. Also, I will check the salt level daily as well. Without any refill into the spa, I would expect the salt level to be stable. Also, the builder might have a leak detection service check out the in-ground plumbing. I will keep you posted.

Thanks again.

Kit

 

[Kit]

As the original poster, I am trying to uncover the mystery of decreasing salt level in my spa. At this point, I am monitoring both the water level & the salt level with the auto fill turned off as (as I have indicated in this thread).

In the meantime, other than splash-out or a water leak in the system resulting in the auto fill diluting the salt concentration, is there any other possible explanation for the falling salt level? I am trying to be a thorough as I can in rooting out the culprit. Thank you kindly.

kit

 

[JamesW]

Water loss and refill is about the only practical explanation for falling salt levels.

It could be test error, but it seems that you have two fairly reliable and consistent methods of salt testing.

You can lose some chloride to chlorine forming volatile chlorinated gases, such as nitrogen trichloride. However, that would be negligible.

 

[Kit]

That confirmed my thinking. Thank you, James.

Kit

 

[Kit]

I am still monitoring the salt level & water level in my spa. And as I indicated previously, I will report back with my readings. In the meantime, I have a question regarding my salt-level testing procedure. How important is it to be consistent when testing? In other words, should testing be done about the same time of day? Would the readings differ if the pump was on or off during testing? Should the water sample be taken from the same depth? Thank you.

Kit

 

[wjr75]

Do you have a hydrostatic valve in one of the floor drains? I have had them leak on me including the one in our main pool this year. I also had one of the plugged ports in one of the spa main drains start to leak.

 

[Kit]

Do you have a hydrostatic valve in one of the floor drains? I have had them leak on me including the one in our main pool this year. I also had one of the plugged ports in one of the spa main drains start to leak.

I don't know if it is a hydrostatic valve. However, for the past week the auto fill has been off & there is no reduction in the water level whatsoever. I have contacted the spa builder who plans to pressure test the plumbing as well.