Combined chlorine high

[Burnt Weenie Sandwich]

Hi everyone thanks for hosting this great site.

I had algae and got rid of it by loosely following the SLAM method. I didn't have time to wait for an FAS-DPD kit to arrive. I realize this was ill-advised but I got rid of it.

Anyway, I took my water in yesterday for testing after it cleared up to see where I stood. My FC was 19.86 and CC was 1.27. CYA was 63. This morning I added 2 lb of chem out. The dosage guide said to add 16 scoops to drop 10 ppm. There were only 12 scoops in the bottle so let's assume I dropped it by 7.5. My test strips roughly corroborate this. I do have an FAS-DPD kit coming in a few days. I apologize for the vague numbers.

There's still a strong chlorine smell indicating the CC is still high. Let's say my FC is around 12 and the CC is still 1.27. Will this CC eventually break down? Should I shock it again to get rid of the CC?

Also, as an aside, how exactly does FC get rid of CC?

Any advice is appreciated. Thanks!

 

[jeffchap]

FC doesn't get rid of CC. UV rays in sunlight break it down, just as they do FC.

 

[mknauss]

Welcome to the forum!

What is 'chem out'?

 

[LFrankow]

Welcome to TFP
If you hold your FC at shock level in relation to your CYA level and maintain it you will then experience an FC loss of less then 1, no chlorine smell as your CC will be less then .5 and your pool will be clear.
Until you can test and post your results for these tests add a gallon of 8.25% bleach per day and brush.
Looking forward to seeing your test results.

 

[Burnt Weenie Sandwich]

Thanks for all the replies.

Chem out is a chlorine neutralizer.

Ok so FC doesn't directly get rid of CC? I guess I assumed it did since adding FC is the solution to getting rid of the smell.

If uv rays are the only thing that lower CC, would I be ok to let it go and allow CC and FC to drop, since My target FC for my CYA is 7-9 and I'm already over it?

What does shocking or SLAMing do to CC?

Need some help understanding the science here I think.

 

[mknauss]

Why would you add a chemical to lower your FC when, if you believe the pool store test, your FC was not an issue? Well below shock level for a CYA of 60.

Thank you for the clarification.

 

[Caco]

Hiya and welcome to the forum
There was no need to lower the chlorine, it was not at a dangerous level when compared to your CYA
See this chart which is on of the cornerstones of TFP
http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

I would reccomend reading that page and undertaking a slam given the pool readings you have

The other cornerstone is reliable accurate home testing of your pool
We find a pool owner at home gets much more reliable results than most pool store testing
We recommend a TF 100 or Taylor K2006C test kit as it has a fas-dpd test for chlorine that can measure up to 50ppm FC. Most prefer the TF 100 as it has more of the tests we use daily. http://tftestkits.net/TF-100-Test-Kit-p4.html

You are right about FC breaking down CC. Some of the CC is also broken down by sunlight (UV) as well
The is extracted from a post Chemgeek (a very knowledgeable chemist) wrote on the subject

Basically the breakdown (oxidation) of Combined Chlorine (CC) occurs continuously whenever there is Free Chlorine (FC) available in the water. Some CC also degrade on their own from the UV in sunlight while others are volatile and may outgas from the pool. There are different kinds of CC and some break down from chlorine more easily than others so some may build up over time. It is unusual to find CC in a properly managed outdoor pool (with good air circulation and sunlight exposure) unless there is a high bather load or large increase in organic matter (e.g. pollen).

The breakdown of chlorine by sunlight does not produce CC. It simply turns chlorine into chloride (salt).

 

[Burnt Weenie Sandwich]

Thanks everyone. I was following that chart on CYA/FC levels. The water was clear and I wanted to get back down to the target maintenance level of 7-9, which is why I addded the neutralizer.

I ordered a Taylor k1515a FAS-DPD kit from Amazon but it won't be here for another 2 days.

So I'm still above target FC. With FC 12 and CC 1.2, CYA 63, do I need to go back up to shock level or will the CC drop at this level? FC is still 10x CC.

Also one person has responded that FC doesn't break down CC and another responded that it does. Anyone care to be the tiebreaker?

 

[jeffchap]

Take Caco's word for it. He quoted Chem Geek on the subject, and he def knows more about it than I do. Sorry, my bad.