First test using kit - high salt but low chlorine?

[k2dak]

Hi all - first time pool owner here looking for some guidance after ditching the local pool company and doing my first test today using the Clear Choice Labs salt water kit:

Total Pool Water Testing Kit, Salt Water – Clear Choice Labs

Below are the results:

CYA = 60
FC = 1
PH = 7.6
TA = 75
CH = 175
SALT = 6000

Looks like the salt is high but the chlorine is low, as if the SWG (which I think is an Astralpool E25?) is not working (however it looks like it is, as when I look at the SWG cell plate window thing, I can see cloudy bubbles being generated)?

The other thing is that the test kit comes with a sample of water with salt at 4000, and when I test this, the test kit shows it as 5000. Is the test kit faulty, or...?

Other random info...

The local pool shop tested it three weeks ago, and the results were free chlorine of 3 and salt at 3000 (and the month before that was free chlorine of 6 and salt at 3500).

Since the local pool shop test three weeks ago, I added one bag of salt, and we have used the pool for the first time ever, for the past five days straight.

Any ideas?

 

[mgtfp]

Welcome to TFP!

The AstralPools have a wide range of 3000-8000ppm salt where they keep working. So, even though salt is on the higher side now, it should still be working, no matter if it's 5 or 6000. I'd recommend to get in touch with CCL and tell them about the difference with the reference sample. I suspect there's something wrong with the reference sample rather than the reagents. I'm sure CCL will be supportive there to find out where the problem is.

Problem with the low FC might be an underlying algae problem that eats up more and more of the produced chlorine.

As a first measure, I recommend to get some liquid chlorine asap and add enough chlorine to get you up to at least 9ppm FC, so you are at the upper target range for your CYA for liquid chlorine pools in the FC/CYA Levels (follow the liquid chlorine table rather than the SWG table until you've got the system running smoothly). You can calculate the required amounts of liquid chlorine with PoolMath.

Then do an Overnight Chlorine Loss Test with the SWG turned off so we can determine if you have algae. If yes, then you need to follow the SLAM Process to get rid of it.

Could you also post a photo of your cell that shows the plates? I recently had a warranty replacement of my AstralPool cell because it wasn't producing enough due to an assembly mistake that lead to the plates not overlapping properly.

And have a good read through the Pool Care Basics to get you started.

 

[k2dak]

Welcome to TFP!

The AstralPools have a wide range of 3000-8000ppm salt where they keep working. So, even though salt is on the higher side now, it should still be working, no matter if it's 5 or 6000. I'd recommend to get in touch with CCL and tell them about the difference with the reference sample. I suspect there's something wrong with the reference sample rather than the reagents. I'm sure CCL will be supportive there to find out where the problem is.

Problem with the low FC might be an underlying algae problem that eats up more and more of the produced chlorine.

As a first measure, I recommend to get some liquid chlorine asap and add enough chlorine to get you up to at least 9ppm FC, so you are at the upper target range for your CYA for liquid chlorine pools in the FC/CYA Levels (follow the liquid chlorine table rather than the SWG table until you've got the system running smoothly). You can calculate the required amounts of liquid chlorine with PoolMath.

Then do an Overnight Chlorine Loss Test with the SWG turned off so we can determine if you have algae. If yes, then you need to follow the SLAM Process to get rid of it.

Could you also post a photo of your cell that shows the plates? I recently had a warranty replacement of my AstralPool cell because it wasn't producing enough due to an assembly mistake that lead to the plates not overlapping properly.

And have a good read through the Pool Care Basics to get you started.

Thanks for the quick reply

Is the Hy-Clor Liquid Chlorine from Bunnings OK, or should I be using something else?

I'll get the chlorine level up, then do the Overnight Chlorine Loss Test, and report back.

Will also follow up with CCL, and try and get a pic of the cell.

Cheers.

 

[PoolStored]

first time pool owner here looking for some guidance after ditching the local pool company

The local pool shop tested it three weeks ago,

Welcome to TFP!!!

Best advice I have is trust your test kit and avoid the pool store testing and advice.

Best,
PoolStored

 

[Bperry]

You might also do the tests again and make sure you followed the instructions exactly, since it’s your first time it’s always good to rule out any test error.

 

[mgtfp]

Is the Hy-Clor Liquid Chlorine from Bunnings OK, or should I be using something else?

The only thing with chlorine really is to make sure that it hasn't been in the shop for months, loosing its strength.

Never bought the Bunnings chlorine, but I assume that it's fine. I think they sell two options: Smaller 5l bottles and larger 15l bottles (I assume with refund to be returned and refilled).

Is the 8000 in your pool size liters or gallons? If It's liters, then 5l of 12.5% chlorine would add 78ppm of FC, if it's gallons (i.e. 30000 liters), then it would be 21ppm. Would be good if you could also add all of your pool information to your signature. Hold your phone sideways to see for example my signature as a template.

You want enough to bring bring FC straight away up to 9ppm, and maybe a second time after sunset to start the OCLT. And then some more to get through the Christmas days.

I assume the next two to three days are not ideal for before sunset tests and testing every few hours to maintain a SLAM. But you should at least make sure that FC never falls below 5ppm, if you decide to deal with OCLT and potential SLAM after Christmas.

Any FC up to SLAM for your CYA-level is safe to swim in. Not sure how much you already read about the FC/CYA relationship. In a nutshell: The way CYA acts as a "sun screen" is that most of the chlorine in the pool is in a chemical bond with CYA, where it is protected from UV light. That also implies that only a small percentage of chlorine is available as "active" chlorine, in chemical terms HOCl or Hypochlorite Acid. Unfortunately, the chlorine that is bound to CYA also shows up in "free" chlorine tests. That means that the FC (as tested with your CCL test) had to be adjusted to the CYA level to yield same amounts of HOCl. Turns out that same ratios of FC/CYA yield the same amounts of HOCl. FC 3ppm at CYA 30ppm is for example equivalent (in terms of HOCL) to FC 8ppm at CYA 80ppm.

The FC recommendations used by the pool industry unfortunately don't take the chlorine / CYA chemistry into account, and treat the required/acceptable FC as independent from CYA. For them, FC 3ppm at CYA 0 and CYA 100 are the same. But the first will be really, really unpleasant and wreck your swim gear in no time (like in a public indoor pool), and the second will end up with a green algae mess.

As an example, SLAM-FC according to the FC/CYA Levels (for example FC 24ppm at CYA 60ppm) is equivalent to FC 0.64ppm with no CYA.

Once FC has been adjusted to the CYA level, CYA adds the benefit that it it "flattens" the influence of pH on the amount of available HOCl. Any pH that has a "7" before the dot is equally acceptable in terms of HOCl, if FC is maintained according to the FC/CYA chart.

Just keep in mind, that FC above 10 makes the pH test always look red. Check and adjust pH before going above 10.

Hope, I haven't overwhelmed you with information here, but I wanted to make sure that you understand the cornerstone of the TFP method, and don't panic when reading about the higher FC recommendations here.

Since adopting the method, I never had algae. Visitors often compliment the clear water and that there is no chlorine noticeable at all in my pool.

 

[k2dak]

Welcome to TFP!!!

Best advice I have is trust your test kit and avoid the pool store testing and advice.

You might also do the tests again and make sure you followed the instructions exactly, since it’s your first time it’s always good to rule out any test error.

Thanks guys - have done a few more tests now and the kit seems to give consistent results.

Is the 8000 in your pool size liters or gallons?

Gallons (I figured this forum was mostly frequented by our American friends?).

I assume the next two to three days are not ideal

Yep - sorry for the late replies, but it has been hectic, with just moving in to this house in the last few months with three kids under 8 (in between working), then hosting the family on boxing day yesterday

Pics of SWG cells attached.

Have added some Bunnings liquid chlorine which has bumped up the FC, and will look to do the OCLT in the next day or two.

Will update signature with more info shortly.

Thanks again to everyone for all the extra info

 

[mgtfp]

SWG looks OK, doesn't have the issue that my one had.
Keep topping up with liquid chlorine and then do the OCLT once you get around to it. Then we'll know where you are.