Salt Reading Too High

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M

mgxzen

Member
Mar 28, 2024
5
Victoria, Australia
Hi there,

Recently purchased a home with a pool. Ive spent the last couple of weeks getting the chemistry right based on TFP standards.

65000 L pool

I did my salt reading and it was 3000ppm. My SWG needs levels at 4000ppm so I added 100kgs of salt which should’ve brought it to around 4500ppm.

I waited a few days for it to dissolve and now my salt is reading at 8400ppm!

This is all using the Clear Choice Labs testing kit (equivalent to the Taylor here in Australia).

My question is, could something be affecting the reading? I’d rather not have to drain my pool if possible.

Last readings
FC 13 (I’ve lowered the SWG output to get this down)
PH 7.2 (I have high alkalinity so this will trend up over time)
CYA 85
TA 125
 
I suspect you have a testing error.

Did you do the salt test again?

What sample size did you test? A 10 ml water sample?
 
mgxzen said:
Yep I’ve done the test twice and got similar results.

I think it is 10 mL. I can confirm in an hour or so
Click to expand...

You would get the incorrect testing result if you were using a 20ml or 25 ml sample size instead of 10ml.
 
aussieta said:
i dont use the ccl test kit
but would suggest that maybe the original test was incorrect
Click to expand...
100 kgs of salt will raise the 65000 L pool by 1,500 ppm. If the original test was incorrect then the pool started at 7,000 ppm? That does not pass reason either.
 
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I think @aussieta is right.

I tried to explain this by assuming that there's something wrong with the test, making the same relative testing error each time. Also assuming that the pool volume is right so we can trust the level change by the salt addition, this gives the equation, introduction the correction factor f for the test:

3000 x f + 1500 = 8400

Solving for f gives us
f = 1500/5400 = 0.277

This means, to get consistency of initial and final salt levels with the salt addition, assuming the same testing error in both tests, the salt levels needed to be:
Initial: 3000 x 0.77 = 834
final: 8400 x 0.277 = 2333.

But this doesn't make sense for two reasons:
1) A correction factor of 0.277 is a bit extreme to account for faulty reagents.
2) The SWG should not have been working with both these levels, especially the initial one.

Aussieta's explanation is the only one that really makes sense to me, something went wrong in the first test.

@mgxzen: Which SWG do you have? Many Oz-models are specified to run up to 8000ppm, so you wouldn't have to drain too much. Winter rain with draining will do the rest.
 
The CCL reagent bottles, especially the little ones that are used for indicators and the salt reagents, are a bit prone to air bubbles. My latest CH reagents had much improved dropper tips, more like the Taylor tips, but I don't think they have rolled them out to all reagents yet, especially not the little ones.

So, another explanation could be that @mgxzen counted mostly air bubbles in the second test. I'd recommend to repeat the test, being as careful as possible to not get air bubbles, and if one is forming to no release it into the test vial, but on a piece of tissue paper.

Try to keep pressure on the reagent bottle throughout the whole test, trying to not suck in air during the test that can form fresh air pockets around the inside of the dropper.

Taylor dropper tips are designed to not be susceptible to air that's trapped around the tip, but CCL dropper tips are, unfortunately.
 
I’ve redone some tests.

First I checked the 4000ppm standard provided in the kit first and I got 4600ppm as a result.

Then I checked my pool water and got 8200ppm.

I have a Zodiac Clear Water LM2-24 SWG.

My only guess is the original test I did was inaccurate but still the numbers don't really add up. Would any other pool chemistry impact the salt results eg. High FC?
 
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mgxzen said:
Hi there,

Recently purchased a home with a pool. Ive spent the last couple of weeks getting the chemistry right based on TFP standards.

65000 L pool

I did my salt reading and it was 3000ppm. My SWG needs levels at 4000ppm so I added 100kgs of salt which should’ve brought it to around 4500ppm.

I waited a few days for it to dissolve and now my salt is reading at 8400ppm!

This is all using the Clear Choice Labs testing kit (equivalent to the Taylor here in Australia).

My question is, could something be affecting the reading? I’d rather not have to drain my pool if possible.

Last readings
FC 13 (I’ve lowered the SWG output to get this down)
PH 7.2 (I have high alkalinity so this will trend up over time)
CYA 85
TA 125
Click to expand...

Geday mgxzen, welcome to the forum,


Have you run a salt test on the 4000ppm standard solution thats provided with the salt test?

The pool size in liters is the most important number to start with, I would double check your pool size in liters.

Really good work with 100kgs of salt, an absolute figure is great. It is really common for people to give us salt quantities in bags which is a dimensionless unit. Our regular salt bags are 20kgs. So you added 5 bags @20kgs? Which would be ~1500ppm in a 65kL pool.

What chlorinator do you have? Did the chlorinator give any indication of low salt?

Had it rained prior to collecting the first sample that gave the 3000ppm result?

Do you have the smart stir?

If you were at 3000ppm, 5 20kg bags would bring you to 4500ppm. I know that was noted. If you’re at 8400ppm now adding 5 20kg bags means you would have been at 7000ppm. I have seen a pool at 7000ppm caused by a pool shop that was calibrating their salt meter with tap water which would give an artificially low level and cause them to advise to add salt when no salt is needed. So that is possible. But a variation between 3000 and 7000 in your testing means there is something wrong there.

I would start by testing that 4000ppm standard.

In the mean time turning the chlorinator down to at least 50% helps protect it from high salt if that is indeed true.

This exact scenario is why I use a salt meter calibrated with a good quality calibration solution.

Edit: Sorry I didn’t see your post while I was posting. You’ve answered some of my questions.
 
mgxzen said:
I’ve redone some tests.

First I checked the 4000ppm standard provided in the kit first and I got 4600ppm as a result.

Then I checked my pool water and got 8200ppm.

I have a Zodiac Clear Water LM2-24 SWG.

My only guess is the original test I did was inaccurate but still the numbers don't really add up. Would any other pool chemistry impact the salt results eg. High FC?
Click to expand...

I didn’t think high FC affects this test but I would rather see a result when your FC is back below 10ppm.

From the 4000ppm standard your test is reporting high. If you’re really at 8200ppm it would be adjusted to 7600ppm. And at +/- 10% you may be closer to 7000ppm which is still high.

If your test is reporting high why did the initial test report so low? A mystery.

Keep your chlorinator turned down and test again when the FC comes down.
 
Hi Mgxzen, when did you buy your kit? Mines about two months old max, I tested my very new 20,000 litre pool which as far as I know had three 20kg bags of salt at new fill in September last year( i remember them), I added another 20kg bag based on shop test two months ago, just before I knew about TFP, after that my CCL test was off the charts at 8000ppm. It didn't add up. I then tested the 4000ppm sample supplied by CCL and it was 5300ppm using a smart stir so I pretty confident in that test, my salt reagents are now exhausted BTW after testing and draining pool water. Two things I learnt I think, my salt was high but not that high and the test is faulty by about a third too high. I've email CCL with no reply which is disappointing.
 
Damon912 said:
Hi Mgxzen, when did you buy your kit? Mines about two months old max, I tested my very new 20,000 litre pool which as far as I know had three 20kg bags of salt at new fill in September last year( i remember them), I added another 20kg bag based on shop test two months ago, just before I knew about TFP, after that my CCL test was off the charts at 8000ppm. It didn't add up. I then tested the 4000ppm sample supplied by CCL and it was 5300ppm using a smart stir so I pretty confident in that test, my salt reagents are now exhausted BTW after testing and draining pool water. Two things I learnt I think, my salt was high but not that high and the test is faulty by about a third too high. I've email CCL with no reply which is disappointing.
Click to expand...

Thanks for the feedback. Good that you reported that to CCL. Brett is usually pretty good in replying. But sometimes it can take a while until he gets back. Give it a week and then follow up.
 

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