27% hydrogen peroxide

[waste]

From what I've read 3% hp will neutralize a similar quantity of 6% bleach in chlorine residual. Is this linear, will the 27% hp I found neutralize 9X as much? (practical experience says no, I tried it this morning on an over chlorinated 1,900 gal. spa, with no results )

{if you need more specifics, the 1900 gal. hot tub was at 9 ppm fc with 1 ppm cc @ 9:00 AM, I dosed it with 1 1/2 tsp 27% to bring the cl down 2 ppm. At 1:00 - the fc was still 9. Did I miscalculate or is the CL 220 (Hayward) feeder just adding too much?}

 

[JasonLion]

Yes, hydrogen peroxide neutralizing chlorine is supposed to be linear. 2.6 oz of 27% to neutralize 1 ppm of FC in 10,000 gallons. So it should have taken out some of your FC level.

 

[waste]

Thanks Jason

I turned down the chlorinator, but folks hopped into the tub before I could redose it I'll try again tomorrow

 

[Poolschoolgrad]

Ted

Here are my calculations based on the information provided by Jason.

1.5 teaspoons is approx 0.25 oz (1/4 oz)
If it takes 2.6 oz to neutralize 1ppm in 10,000 gallons then it will take only 0.494 oz (1/2 oz) to neutralize 1 ppm in 1900 gallons.
Basically 3 teaspoons for each 1 ppm.
To lower the chlorine by 2 ppm would require 0.988 oz (1 oz) or roughly 6 teaspoons or 2 TABLEspoons.
Adding only 1.5 teaspoons (0.25oz) would only change the FC by 0.5 ppm (1/2 ppm) which could have easily been replaced by the tablet feeder in a relatively short time period or 0.5 ppm could be lost in testing error of even the most careful tester.

With any luck, the bather load from tonight will take care of 2 ppm chlorine.
At least you will know how to solve the problem next time. :-D

PSG

 

[JamesW]

It would probably help to reduce the number of tabs in the feeder. You can't rely completely on the feeder control valve because the tabs are sitting in water and continue to dissolve even if the valve is completely closed. When the valve is reopened, the concentrated chlorine comes out and overchlorinates.

 

[waste]

Thank you all!

I'm all to well aware of the # of pucks problem - I keep ~ 1 1/2 in and have the dial set to ~ the lowest I can

However, as anyone with experience with these units knows that a little debris will clog the feed and, on small pools finding the "sweet spot" is difficult, at least.