Indoor, in ground pool high combined chlorine

i_intub8_u

Well-known member
Nov 13, 2023
90
Wisconsin
Pool Size
17000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
CircuPool Core-55
Hello everyone,
I just purchased a new home. It has a 17,000 gallon indoor, inground, geothermal heated pool. It’s 14 years old, original vinyl liner and all original pool equipment. It wasn’t used much by the previous owners, but was maintained by the local pool company who built it when new. It has a Pentaire cartridge filter.

When I bought the house, the pool water had a green tint to it, but was clear to the bottom even in the deeper parts. Pool company said it was safe to swim in, and thought the green tint may have been from all the iron in the well water in my area. I have an iron filter for the house water, but the pool and irrigation system are fed pre-iron filter.

When tested they said the TDS were extremely high and suggested I drain the pool down to 6” deep and fill with fresh water (they tested my fill water and said it would be fine).

So I drained the pool and filled with fresh water a few weeks ago. Pool was green after filling. Again tested the water with the pool company and they had me add four, 3” pucks of chlorine tabs to the skimmers, 2lbs of shock with blue algaecide, 6 lbs of balance pak 300 (to raise Ca) and 2.5lbs of pH reducer. It was still pretty cloudy and green so I poured a gallon of liquid standard bleach in the pool.

Pool became clearer but still sort of has a film on the surface. Here are the latest tests results from the pool company test (for “free” as long as I buy pool chemicals from them):

Free chlorine: 0.6
Total chlorine: 6.6
pH: 7.5
Total alkalinity: 133
Calcium hardness: 93
CYA: 45
Optimizer: 11
Phosphate: 4000
TDS: 1600

On their printout, it says comfort is 1 out of 5 stars, clarity is 4 out of 5 stars, and protection is 3 out of 5 stars.

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. I’m realizing now that the combined chlorine is likely the culprit for that.

I did just put in 32oz of aqua doc phosphate remover in the pool (left from the previous owner).

The pool company had me add more pak 300 to raise Ca some more and wanted to let the chlorine “balance itself out.” Otherwise he said I’d need to add 17lbs of chlorine tabs.

I’ve read about the SLAM. Is that what I should do now? I want to get my pool chemistry spot on. Any help would be appreciated! Thanks!
 
Welcome to TFP.

First of all stop throwing chemicals into your soup.

I suspect you added MPS shock that shows as CC for a while. Read...


Get your own test kit - Taylor K-2006C or TFT Test Kits

Download PoolMath

Until you get your own test kit pour 1 gallon of 10% liquid chlorine into your pool daily.

When you get your test kit post the results of your tests and we will figure out yoru next steps.

In the meantime review...


and fire the Pool Company.

And stop putting tablets into your pool. Your CYA is already too high for an indoor pool and the tablets are just adding more.
 
Welcome to TFP.
We do not believe in pool store testing, because, as you indicated, it is not free if you are purchasing $400 of unnecessary chemicals.
With an indoor pool, you do not need to have CYA. The CYA is coming from the tablets. Stop using them and switch only to liquid chlorine.
The other algaecide is not helping either.
The one test that the pool store can help with is an iron and copper test but that is not shown.
Please purchase a proper test kit and the cost will offset all the additional chemicals the pool store is selling you.
Look at
Test Kits Compared

If you plan to SLAM then you need this test kit.
 
Get the well water tested at a well water testing lab.

Check with your city and state government for a well water testing department.

They can either test the water for you or they will refer you to a qualified testing lab.

You might have some sort of contamination in the water.

Maybe hydrogen sulfide or other types of unpleasant chemicals.

For an indoor pool, I would recommend a good UV system.
 
An indoor pool is best with 20-30ppm of CYA to buffer the harshness of the chlorine.

Thanks for clarifying that, I should have completed my thought process that adding tablets would continue to increase CYA which is not necessary to be high. Agree that some CYA is needed.
 

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Get the well water tested at a well water testing lab.

Check with your city and state government for a well water testing department.

They can either test the water for you or they will refer you to a qualified testing lab.

You might have some sort of contamination in the water.

Maybe hydrogen sulfide or other types of unpleasant chemicals.

For an indoor pool, I would recommend a good UV system.
It does have a UV sanitizer, but the pool company is pretty sure the bulb is burnt out. But who knows if some other component of the UV sanitizer is broken. I was just assuming it wasn’t working. I can source a replacement bulb for it and try installing that.

Well water test included above and looked ok from the well testing company.
 
That is a basic test and you might need further testing to make sure that there are no issues.

Get the test kits and then get the water balanced and filtered to see if the problems persist.

Maybe get a SWG and a UV setup to help with CCs that form from human wastes.
 
Make sure that the UV equipment is working.

You can check the power, amperage and voltage to verify operation.

Get the water fully balanced using your FASDPD test kit and do continuous filtration.

Make sure that the filter is clean.

UV is mostly good to address CCs and it should be available when CCs accumulate, but UV also destroys FC, so you can turn it off when there are no CCs.
 
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When was the filter cleaned?

You should remove the filters and clean them thoroughly.
The pool company comes and changes the cartridge every 6 months and cleans the used one and then stores it until the next rotation. They just changed it at the pool inspection when I bought the house in September. And I know they changed it because I was there when the pool guy exchanged them.
 
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