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Thread: Worry about PH after adding liquid chorine from the pool store

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    trevorfl's Avatar
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    Worry about PH after adding liquid chorine from the pool store

    I am having problem with my CYA for a while now.

    First, my numbers: (As of 11 AM today)

    FC = 1.6*

    CC = 0.0

    TA = 100

    CH = 250

    PH = 7.6

    CYA = +90*

    My test kit is Taylor R-2006c and the pool is plastered.

    From Orlando, FL

    I saw a table somewhere in the forum with the recommended FC depending on the reading of the CYA.

    Now I hope I did not do something wrong. I added liquid chlorine (from the store). Now my concern is that I added to much.

    The new reading at 6 PM:

    FC = 13.6

    CC = 0.2 or 0.5 depending on the level of the water (10ml/25ml

    TA = 100 (same)

    CH = 250 (same)

    PH = 7.8! maybe a little more.

    CYA = +90*


    I knew that adding liquid chlorine was going raise the PH. My concern is that I don't want to damage anything. I was reading somewhere that it will get back to "normal" eventually.

    Should I add muriatic acid now? Or will it safe to to wait untill tomorrow and take another reading.

    I know I have to drain the pool (close to 2 feet) and refill. Will do it soon but for now I can't .


    Thank you in advance for your help.

    Trevor

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    Richard320's Avatar
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    Re: Worry about PH after adding liquid chorine from the pool store

    The chlorine didn't raise the pH so don't try to lower it with acid. What happened is that the high levels of chlorine reacted with the pH reagent which makes it read falsely high. Pictures When the FC drops below 10 you should get a normal pH reading.

    Your FC is a bit high, but far below shock level for 90 CYA so there's no reason you can't swim in it. Pool School - Chlorine / CYA Chart
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    Isaac-1's Avatar
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    Re: Worry about PH after adding liquid chorine from the pool store

    Liquid Chlorine / Bleach is nearly pH neautral, so I have to ask why you thought it would raise your pH? Many people think Liquid Chlorine raises pH when they switch to it from trichlor pucks, because their pH level goes up, the truth is that the trichlor is extremely acidic which was likely keeping their pH down before they switched to Liquid Chlorine.
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    Re: Worry about PH after adding liquid chorine from the pool store

    First, welcome to TFP Trevor! I type slowly so most of what I am saying is repeating, but I will post it anyway

    Second, a pH of 7.8 would not be a problem as it is plenty acceptable. However that brings me to:

    Third, the pH test is not accurate when your FC is above 10, so odds are that your pH is lower than you are reading. Let your FC come down on its own and you will be able to get a more accurate pH reading.

    As you mentioned, an appropriate FC is directly related to your CYA, here is the chart you mentioned: Pool School - Chlorine / CYA Chart At 90 CYA you want to maintain your FC above 7 at all times. Bringing your CYA down will be quite beneficial in the future.

    Also, the K-2006 instructions recommend using 25 ml of water for your FC/CC test, but to conserve reagents you can use 10 ml with a single scoop of powder and each drop is 0.5 ppm. For most situations that is plenty precise enough and will use less than half as much reagents.
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    Re: Worry about PH after adding liquid chorine from the pool store

    Adding chlorine DOES raise the pH, but when the chlorine gets used/consumed the pH drops back down. Specifically, starting with your numbers I calculate that the pH would have risen from 7.6 to 8.2. Also, if you read the pH test fairly quickly, then 13.6 ppm FC isn't going to give you a false reading. Your pH is very likely to be at 8.2 if your initial reading was correct (not sure why you think it's 7.8).

    So if you intend to keep the FC higher and not let it fall, because of your higher CYA level, then yes you should add some acid to lower it. You could wait for your FC to drop to 10 ppm or so before checking the pH again and then adding acid just to play it safe, but I see nothing inconsistent in your numbers.

    Again, hypochlorite sources of chlorine DO raise the pH upon addition. They are only close to pH neutral when the added chlorine is consumed/used. This means that ongoing use of such chlorine doesn't keep having the pH go up and up, at least not quickly (there is a small amount of excess lye in chlorinating liquid and bleach). However, in your situation, you are raising the FC fairly permanently so the rise in pH from your chlorine addition will also be fairly permanent and therefore needs adjustment by adding acid to lower the pH.
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    Re: Worry about PH after adding liquid chorine from the pool store

    Thank you all for your quick response.

    So, I don't have to worry as long as my numbers of FC is close to 7 or 8. Give or take. This is information is very helpful to me. And thank you for the tip on how to save reagent by using the 10ml instead of 25 and only one scoop of the reagent.

    I will post back with new numbers as I take new readings regarding this issue. I will not test the PH at least untill my FC is below 10 and above 7.

    I am very glad that you all took the time to help me.


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    trevorfl's Avatar
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    Re: Worry about PH after adding liquid chorine from the pool store

    I came back to say Thank You! to all of you who responded with smart solution to take care of my pool. My pool is crystal clear now. (Let's hope Erika does mess with it) And you guys are correct, never trust your pool store 100%. For instance, I just find out that they were giving me recommendations thinking that my pool was a 12K, when it is actually a 15K. Go figure.

    Have a great weekend all

    Trevor

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    Re: Worry about PH after adding liquid chorine from the pool store

    Quote Originally Posted by trevorfl View Post
    I came back to say Thank You! to all of you who responded with smart solution to take care of my pool. My pool is crystal clear now. (Let's hope Erika does mess with it) And you guys are correct, never trust your pool store 100%. For instance, I just find out that they were giving me recommendations thinking that my pool was a 12K, when it is actually a 15K. Go figure.

    Have a great weekend all

    Trevor
    You have a great test kit, so don't bother even taking water to the pool store for testing. In most of Florida pool stores are a great place to buy liquid chlorine, sometimes a good place to buy muratic acid (Lowes/Home Depot often beat pool store prices) but they provide very little else you need.

    Get comfortable with your test kit, use Pool Math to calculate additions and enjoy your pool.
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