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Chlorine Demand

May 15th, 2007 · 1 Comment

Just came from the pool store. Man says my pool has a chlorine demand.
I.G. 20×40 vinyl
24,800 gal.
Test results:
total chlorine 2.7
free chlorine .0
Ph 7.4
t/a 155
total hardness 53
CYA 40
TDS 500
Temp. 85
Saturation Index -0.5
He’s running another test and will call me in the morning with
results. But He said that the way it looks right now, I have 2

choices. Which are:
1) Drain down to the first step level and refill & retreat, or
2) Add a massive dose of Chlorine (maybe as much as 100#)Which may
lead to other things becoming unbalanced.
Your comments, Please
Thanks, Arlee

Tags: chemicals

1 response so far ↓

  • 1 Adeline Sang // May 16, 2007 at 6:38 am

    from those test results it sounds like you have what is referred to as
    chlorine lock or combined chlorine. combined chlorine has a very
    chloriney smell because it is actually chloramines. chloramines are the
    used up form of chlorine. you need to have free chlorine which can only
    be tested for with a dpd test kit. most homeowners use an oto test
    kit. anyway, i don’t think draining will help that problem the only
    way to get rid of chloramines is to use breakpoint chlorination, also
    referred to as shocking or superchlorination. 100 pounds sounds like a
    ridiculous amount to achieve that though. perhaps he meant ten pounds.
    I would recommend shocking and then retested a day or two later.
    personally, i would increase my cya and lower my TA based on those test
    resuls.
    Paul

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