Indoor, in ground pool high combined chlorine

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If the chlorine is getting used up, then the contamination is probably getting oxidized.

The main problem is that we do not know what the contamination is or the concentration or if it is one thing or several things.

So, it becomes difficult to predict how long the SLAM will take.

It might break in a day or two and it might take weeks.
 
JamesW said:
That is a high number for a fresh fill.

Test the water for Salinity using a good conductivity meter and using a K-1766.

That will give us an indication of the TDS caused by salt and the TDS that is caused by dissolved solids other than salt.

Note: With the meter, set the meter to "Salinity" NOT "TDS".
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1600 was before draining and refilling. But after the refill, the TDS were 1500 (so not a big change :().

I’m talking to the local health dept/water testing lab and they seemed stumped that adding that much chlorine hasn’t made the CCs budge.

They are getting back to me with a list of what metals they can test for. They suggested it might be cheaper in the long run to drain and fill from a known good source of water. But that still doesn’t tell me what is in my well water. They said it should be safe since it was negative for bacteria and nitrates (but still).
 
i_intub8_u said:
They said it should be safe since it was negative for bacteria and nitrates (but still).
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Hydrocarbons, like benzene etc. are not safe to have in the water that you use for drinking, swimming, showering etc.

There is definitely some sort of contamination in my opinion and I would want to know for sure what it is.

Check for trihalomethanes and haloacetic acids.
 
JamesW said:
Hydrocarbons, like benzene etc. are not safe to have in the water that you use for drinking, swimming, showering etc.

There is definitely some sort of contamination in my opinion and I would want to know for sure what it is.

Check for trihalomethanes and haloacetic acids.
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Right. I will talk to the lab about testing for these. Thanks.
 
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i_intub8_u said:
It had some foam on the top.
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Thanks.

JamesW this is a confirmation of presence of TOC. If it holds a foam there is definitely TOC present.

It looks to me online that Badger Laboratories | Water Testing | Lab Testing should be able to assist with the water samples. I don't think they are accredited, so likely less costly. However, for this purpose, accreditation may not be required.

I would concur with the suggestion of drain and refill from some other water source to sort the pool quickly. We would not normally fill a pool from bore due to the presence of too many unknowns. In addition the aquifer can change without notice and this can upset everything.

At the same time I would get some lab work done on the bore water it is worth knowing what is happening at least a drinking, metals and organic package.
 

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While I’m waiting for the lab testing, think I should add 4 gallons of the 12.5% bleach just to see? 3 gallons is what Pool Math calls for to go from a FC of 0-20. Just to see if I can break the CC?
 
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JamesW said:
I would just continue the SLAM.

The chlorine will take time to oxidize the contaminant.
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Ok. Will do.

I took the pool water to 2 pool stores just to see what their tests would say. I’m “lucky” enough to have 2 pool stores within 2 miles of my house.

The first pool store (the one that had been testing the water for the prior owner) came back with this:
FC 0.5
TC 6.6
pH 6.6
TDS 2000 (up from 1500)

The TC from their tests prior to starting the SLAM was in the 8s with a FC of 0.5. So maybe some progress?

The other pool store got:
0 FC
2.9 TC
His test strip tested lightly positive for nitrates. The well water was tested when I moved in and had a negative result for nitrates/nitrites/coliform bacteria. He said if there’s actually nitrates, that would be consuming all the chlorine I’m adding. But would that result in a high CCs? Otherwise he was thinking it could be a high ammonia contaminant. But he wasn’t really sure. He seemed alarmed when I told him I had added around 25-30 gallons of bleach in the last 3-4 days trying to eliminate the CCs.

Obviously idk how accurate either of the stores’ testing is, but at least the general trend from the first pool store is my CCs have come down a little. Or am I just hoping that to be true?

Just added another 3 gallons of bleach. Will check again in the morning. Gotta go buy another 16 gallons of 12.5% bleach I guess.
 
It does seem that you’re making progress. Albeit slowly.
If you had the ability to test & dose more frequently (multiple times per day/every few hours if you can swing it) that would help speed the process along.
Got any pressure washing or janitorial suppliers in your area that you could purchase bulk liquid chlorine from? Definitely would be worth looking into.
I am quite blessed that we have a local mom & pop pool store that carries fresh liquid chlorine year round in refillable 2.5 gal jugs for a good price.
When you get your alternative testing done be sure to test both the pool water & the fill water.
 
i_intub8_u said:
He said if there’s actually nitrates, that would be consuming all the chlorine I’m adding.
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The nitrogen atom can have 0 to 8 electrons in the outer valence electron shell.

The nitrogen in nitrate has 0 electrons in the outer valence electron shell, so chlorine will not react with it.

The nitrogen in nitrate is fully oxidized (+5), so it cannot react with chlorine.

Chlorine can react to nitrite, but it is unlikely that you have nitrite.

Even if you have nitrite, it will get oxidized to nitrate as chlorine takes the remaining two electrons.

Once the nitrogen atom is in the nitrate state, there are no more available electrons to get and there is no reaction.

Chlorine oxidizes something by taking electrons.

Electrons........Oxidation State

0..........................+5 (Nitrate).

1..........................+4

2..........................+3 (Nitrite)

3..........................+2

4..........................+1

5............................0 (Nitrogen gas).

6..........................-1

7..........................-2

8..........................-3 (Ammonia).

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Below is the nitrogen atom with 5 electrons in the outer shell, which gives it a 0 oxidation state since the total number of electrons equals the total number of protons.

This is elemental nitrogen, which is nitrogen gas N2.

From here, the atom can gain up to 3 electrons or lose up to 5 electrons.

Gaining electrons is called reduction because the oxidation number decreases because electrons are negative.

Losing electrons is called oxidation and the oxidation state increases.

Protons have a +1 charge and electrons have a -1 charge.

7(+1) (Protons) + 7(-1) Electrons = 0 oxidation state.

The two inner electrons do not react; only the outer electrons can be gained or lost.
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There is probably some sort of chemical or chemicals in the water.

Part of the problem is that we do not know what chemicals are in the water or how much of each chemical there is.

If you can find out, that would help a lot.

If you cannot find out, then you have to decide to continue to SLAM and hope for the best or drain and refill if you have a different source of water and you can drain without damaging the pool.

With a vinyl liner, the liner has to be held in place by water pressure, so you cannot drain completely without losing the setting of the liner.

Also, ground water can damage the pool if the ground water is high enough.

Note: Do not drain unless you are 100% sure that it is safe to do so.

Draining - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
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Nitrogen and carbon based molecules have hydrogen atoms attached, so you will probably see the pH and TA drop as the chemical is oxidized.

As the nitrogen or carbon atoms are oxidized, the hydrogen ions are released and hydrogen ions are basically acid, which is why the pH and TA will go down.

Methane has 4 hydrogen atoms attached.

Chlorine substitutes for the hydrogen and bonds in its place to form products like trihalomethane.

The chlorine pulls on the electrons but the carbon holds on tight, so they are locked together because they are both holding onto the electrons trying to keep them.

UV can knock loose the electrons from the carbon, which makes it easier for the chlorine to take them.

Carbon is similar to nitrogen.

It has 4 electron in the elemental state and it can gain up to 4 electrons or lose up to 4 electrons.

Methane has a carbon atom with 8 electrons in the outer shell, which gives it a -4 charge.

To oxidize the carbon to carbon dioxide with 0 electrons in the outer shell, the chlorine has to take a total of 8 electrons from the carbon atom, which is why it takes a lot of chlorine to fully oxidize a hydrocarbon molecule like methane.

The carbon in carbon dioxide has 0 electrons in the outer shell, which gives it a +4 charge.

As the carbon becomes carbon dioxide gas, the CO2 gas leaves the pool and the carbon is completely gone.

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Why Does pH drop When Treating Ammonia With Liquid Chlorine?​

Oxidizing ammonia creates acid by releasing hydrogen.

More than 95% of ammonia is in the form of the ammonium ion (NH4+)

2NH4+ + 3OCl- --> N2 + 3H2O + 2H+ +3Cl-

When adding 12.5% sodium hypochlorite (liquid chlorine) to a pool to oxidize ammonia, every gallon of liquid chlorine will create the equivalent of 15 ounces of 31.45% hydrochloric acid.

10 gallons of 12.5% liquid chlorine added to 25,000 gallons of pool water with ammonia will lower the TA by about 23 ppm or the equivalent of adding 150 ounces of full strength 31.45% muriatic acid.

Every 8.53 gallons of 12.5% liquid chlorine is equivalent to about 1 gallon of 31.45% acid.

CC - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
i_intub8_u said:
Had some people over to swim, but after an hour of so in the pool room and water, people began to get coughing and watery eyes so we all got out and showered.
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This might be due to either chloroform or nitrogen trichloride or some other chemical produced that is either a gas or easily volatilized depending on the type of molecule in the water.

You might have some nitrogen and some carbon based chemicals, but you will need a lab to find out.
 

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