CC, SLAM & max safe chlorine to swim

[incredible-bulk]

Hi guys, 1st post and I have a few questions.

I only have an above ground pool. Not very big, under 7000 litres.

I am experiencing elevated combined chlorine. It seems to fluctuate between 0.8 and 1.5ppm. I did a SLAM on it, albeit an incorrect one because I raised the FC to breakpoint and didnt maintain it there.
However, it had some success because I did manage to get the CC below 0.5ppm down to 0.39ppm.

My questions are this,

1) Can anyone give me some pointers why my CC rises despite seeing no obvious reasons for it to? Its gone up gradually this week despite nobody going in the pool. No visible signs, the water looks crystal clear.

2) I will do an overnight chlorine test however I have tested FC in evening and then early morning and FC was within expectations. Might have been slightly above 1ppm loss but the sun had risen for a few hours in the morning thus I believe accounts for the slight loss. Are there any other factors that can cause CC when nobody has been in the pool and no algae present?

3) I have been reluctant to SLAM because I havnt wanted the pool to be out of action. I just know that once I take it out of action the weather will turn good! My last question is after performing a SLAM, what level of FC would you let the pool come down to before deeming it safe to swim in?

Last test data looks like this.

FC - 4.45
CC 1.3
pH - 7.9
TA - 87
CYA - 50
CH - 207

I use Cal-Hypo 70% to maintain chlorine levels and im assuming its ok to SLAM using that instead of liquid chlorine?

Thanks.

 

[Mdragger88]

You don’t need “breakpoint chlorination” just the SLAM Process .
It is safe to swim with fc anywhere between minimum & slam level for your cya so long as you can see the bottom of the pool for swimmer safety .
So anywhere between 4ppm & 20ppm with your cya of 50.
FC/CYA Levels
The cal hypo will increase your ch & is also known to cause cloudiness in large doses. Stick with liquid chlorine for slam.
How are you testing the water?

 

[HermanTX]

Welcome to TFP.
With a CYA of 50, that requires a SLAM level of 20ppm for FC. As you stated you did not maintain it.
With a CYA of 50, your target range for FC is 6-8ppm. You can swim upto SLAM level of 20ppm so long as you can see the bottom of the pool. S this link

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

I suspect you have some algae hiding. Do you have a ladder or in the skimmer? Check those areas very closely as that can cause the higher CC. j

 

[incredible-bulk]

You don’t need “breakpoint chlorination” just the SLAM Process .
It is safe to swim with fc anywhere between minimum & slam level for your cya so long as you can see the bottom of the pool for swimmer safety .
So anywhere between 4ppm & 20ppm with your cya of 50.
FC/CYA Levels
The cal hypo will increase your ch & is also known to cause cloudiness in large doses. Stick with liquid chlorine for slam.
How are you testing the water?

Hi thanks for the response. I hear you re: the disadvantages of cal hypo. However, it is what I have and money is tight. Am I right in assuming it will do the job despite the downsides?

Im testing using hanna photometers.

Welcome to TFP.
With a CYA of 50, that requires a SLAM level of 20ppm for FC. As you stated you did not maintain it.
With a CYA of 50, your target range for FC is 6-8ppm. You can swim upto SLAM level of 20ppm so long as you can see the bottom of the pool. S this link

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

I suspect you have some algae hiding. Do you have a ladder or in the skimmer? Check those areas very closely as that can cause the higher CC. j

I just brushed the pool and noticed green in the fold of the liner where the pool wall meets the bottom of the pool. Well ill be Darn!

 

[Mdragger88]

Is this an intex style temporary pool?
If so be sure to get all up in all the flaps! I used to use a regular house broom with plastic bristles for that.
What type of filter do you have?
If it is very small & the cal hypo causes cloudiness you will just have to wait it out.
Is there any reason why you don’t just drain, scrub & refill the pool (assuming this is an intex style pool). It would be alot cheaper & faster than trying to do the
SLAM Process with a small filter.
As for the testing- that’s some very expensive test equipment for a small pool.
Most photometers that are somewhat affordable for the average homeowner aren’t recommended due to their accuracy & limitations - not sure if the ones you have are affected by these or not.
We recommend drop based testing.
Here’s more about that

Pool Test Kits - Further Reading

www.troublefreepool.com

Have you seen the guide for temporary pools?

Guide for Seasonal/Temporary Pools

Smaller seasonal pools can see just as much enjoyment as their larger counterparts. In this guide we'll show you how to maintain your temporary pool.

www.google.com

 

[incredible-bulk]

Is this an intex style temporary pool?
If so be sure to get all up in all the flaps! I used to use a regular house broom with plastic bristles for that.
What type of filter do you have?
If it is very small & the cal hypo causes cloudiness you will just have to wait it out.
Is there any reason why you don’t just drain, scrub & refill the pool (assuming this is an intex style pool). It would be alot cheaper & faster than trying to do the
SLAM Process with a small filter.
As for the testing- that’s some very expensive test equipment for a small pool.
Most photometers that are somewhat affordable for the average homeowner aren’t recommended due to their accuracy & limitations - not sure if the ones you have are affected by these or not.
We recommend drop based testing.
Here’s more about that

Pool Test Kits - Further Reading

www.troublefreepool.com

Have you seen the guide for temporary pools?

Guide for Seasonal/Temporary Pools

Smaller seasonal pools can see just as much enjoyment as their larger counterparts. In this guide we'll show you how to maintain your temporary pool.

www.google.com

Thanks for the info. Yes it is just a small above ground pool. I have quite a hefty sand filter attached so no issues with that. Probably turns the entire pool over in an hour so the pump/filter is very much overkill.

Re the photometers, they are serious overkill for my situation also but i already have them from keeping koi and tropical fish. A couple of reagents here and there is cheaper than buying a whole new drop test kit and it would he a bit stupid of myself to “downgrade” to a drop test kit if you know what i mean.

Why dont i drain down the pool instead if using chemicals? Well its a bit like my photometer situation. I already have the chemicals so its already paid for. Draining and filling the pool again would be a significant cost here in the UK because we are on a water meter. All things considered its probably worth my while making the water already in the pool good rather than draining and refilling. The water is crystal clear, just need to get the CC down.

Cheers.