Chlorine Locked?

[chem geek]

It's too bad we don't yet know if sodium percarbonate will work at this late stage. Otherwise I'd suggest it. Does the pool store near you carry any small containers of ProTeam® System Support? Or can you order a small jar from The Chemistry Store. You could then try a small amount in a 2-gallon bucket of your pool water -- about 1/8th of a teaspoon -- to see if it can oxidize the CC.

Another alternative would be your own combination of sodium carbonate with hydrogen peroxide since sodium percarbonate is technically one part sodium carbonate with 1.5 parts hydrogen peroxide. By weight, 1 pound of sodium percarbonate is 0.675 pounds sodium carbonate and 0.325 pounds hydrogen peroxide. So you can use pH Up product or Arm & Hammer Super Washing Soda for the sodium carbonate. This would then be closer to 1/16th of a teaspoon of pH Up / Washing Soda. As for the hydrogen peroxide, you can easily get 3% solution from a drug store (though you probably have more concentrated as oxidizer for your pool, we don't know its concentration for sure). The amount needed is 1 teaspoon.

If you have FC from chlorine, then the hydrogen peroxide will neutralize that so we'll need to increase the dose accordingly. The rough rule-of-thumb is that a volume of 3% hydrogen peroxide neutralizes the same volume of 6% bleach. So for the 2 gallon bucket, 10 ppm FC gets neutralized by 1/4 teaspoon of hydrogen peroxide.

So let's make this simple and have you add pool water to a clean 2-gallon bucket. Wait one hour and then measure FC and CC. Add 1/8th of a teaspoon of pH Up / Washing Soda, mix, then add 2-1/4 teaspoons of 3% hydrogen peroxide and mix. Then wait for 1 hour. Then measure the FC and CC. Wait for 8 hours and measure again. Wait for 24 hours from your initial addition and measure again. This dosage is double the amount recommended by Orenda, but should tell us whether or not sodium percarbonate will work. You should definitely see the FC going to 0, but we'll see if the CC drops as well. If it does drop enough, then we'd add chlorine back into the bucket using 6% bleach, 1/4 teaspoon at a time, until FC registers again and make sure that CC doesn't return.

[PoolDoc]

In the earlier conversations I had with Chem_Geek regarding this situation, the possibility that you were breaking down stuff trapped on the filter came up. The fact that you had so much junk on the filter makes that possibility even more significant.

So . . . besides doing the 'chemistry experiment' above, you might want to
#1 - Change your sand, &
#2 - Use skimmer socks (Amazon link: Jed Industries 80-852 Pool Skimmer Sock )

BTW, if Chem_Geek's experiment works, you can get washing soda at Walmart, and can use Baquashok for the peroxide source. So the results may lead directly to a practical solution.

[reesie]

We're doing the experiment above. We put the 2 gallons pool water in a clean bucket, waited one hour. Tested 0 fcl, 7.5 tcl, 7.5 ccl. Put ph up, mix, put hydrogen peroxide, mix, waited 1 hour, measured, fcl 0, tcl 5, ccl 5. We'll see what we get tonight after waiting 8 hours then tomorrow night after 24 hours.
Also, we're going to change the sand ( I had told my husband the other day that I thought maybe that was part of the problem since all of that junk was in the filter). I'm glad to know I'm not totally alone in my thinking! I'm also going to get the filter socks. I never heard of them before.
I'll post the results.

[CarlD]

Skimmer socks are also called "filter savers". Brand doesn't matter.

I find bleach, washing soda and borax all at the local supermarket, which is far closer than the nearest WalMart.

Carl

[reesie]

Tonight's results on the bucket of pool water were:
fcl 0
ccl 0
I did the test twice and it was totally clear. I'll check again at 9:00 pm tomorrow night.
After checking tomorrow night, Chem geek said to add 1/4 tsp. bleach at a time until fc registers again and make sure that cc doesn't return (hopefully). How long would we wait between adding each 1/4 tsp. of bleach?

[chem geek]

So far, so good. It looks like it does reduce CC taking somewhere between 1 and 8 hours to do so. After you start adding bleach after measuring tomorrow night, you can measure within an hour and then add more bleach. Repeat until you start to measure FC that should then hold and we'll see if the CC returns or not.

If the CC returns after adding bleach, then that would mean the hydrogen peroxide was just acting as a reducing agent to get rid of CC, but then adding a chlorine oxidizer again would recreate CC. If instead the CC doesn't return after adding bleach, then that means the hydrogen peroxide oxidizes the CC to truly get rid of it. Let's keep our fingers crossed that the latter is what is happening.

[waterbear]

So
If the CC returns after adding bleach, then that would mean the hydrogen peroxide was just acting as a reducing agent to get rid of CC, but then adding a chlorine oxidizer again would recreate CC. If instead the CC doesn't return after adding bleach, then that means the hydrogen peroxide oxidizes the CC to truly get rid of it. Let's keep our fingers crossed that the latter is what is happening.

Also, if the CC returns but at a lower level then the process is working but might need to be repeated.

[reesie]

Here are the readings tonight.
7:00 pm
fcl 0
tcl 0
ccl 0
added 1/4 tsp. bleach

8:00 pm
fcl 0
tcl 0
ccl 0
added 1/4 tsp. bleach

9:00 pm
fcl 2.5
tcl 2.5
ccl 0
added 1/4 tsp. bleach

10:00 pm
fcl 4
tcl 4
ccl 0
added 1/4 tsp. bleach
That's going to be it until tomorrow night after work.