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Thread: size of pool - new estimate after shocking

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    size of pool - new estimate after shocking

    Hi all. The latest is that I've recently shocked the pool over a period of about three days. Not 100% sure I needed to shock. I went ahead because (1) I knew it hadn't always been dosed appropriately (2) my son was saying it looked cloudy underwater though it was clear from my vantage point outside the pool (3) leaves, pollen, twigs are out of control, they fall as fast as I remove them. After shocking, the water looks more sparkly and the view of the bottom is sharper. So I conclude that it probably was in the early stages of developing algae before shocking.

    My question is whether my pool size needs to be adjusted for proper bleach dosing. It almost certainly does, but I want to confirm with the experts here.

    Pool calculator indicated that I should add 815 oz of bleach for a 23K pool. I was scared of such a high number and decided to add only 626 oz. After testing I found that the 626 oz of bleach resulted in overshooting the shock target of 28 ppm Cl (for a CYA of 70) by 2ppm (reading was 30 ppm Cl). So I decided that our pool is likely something like 17,500 gallons not 23,000. Is this about right?

    One more thing -- Right before shocking I did a long overdue soaking and cleaning of our four cartridge filters - they were surprisingly dirty and slimy - using tsp and in some areas I found Qtips helped de-gunk the folds. When should this be repeated, end of May? I shocked mid April.

    Thank you!
    HoustonMom

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    linen's Avatar
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    Re: size of pool - new estimate after shocking

    Quote Originally Posted by HoustonMom
    After shocking, the water looks more sparkly and the view of the bottom is sharper. So I conclude that it probably was in the early stages of developing algae before shocking.
    Make sure you pass all three end of shocking criteria (in my sig) simultaneously. Next time you are uncertain, you can always do the OCLT to check.

    Quote Originally Posted by HoustonMom
    My question is whether my pool size needs to be adjusted for proper bleach dosing. It almost certainly does, but I want to confirm with the experts here.
    Sounds like you have a reason to adjust, and going lower is safer than going higher. Are you certain you had the right concentration in the poolcalculator.com for the bleach. 8.25% bleach has started to dominate the market.

    Quote Originally Posted by HoustonMom
    One more thing -- Right before shocking I did a long overdue soaking and cleaning of our four cartridge filters - they were surprisingly dirty and slimy - using tsp and in some areas I found Qtips helped de-gunk the folds. When should this be repeated, end of May? I shocked mid April.
    When your pressure goes up 25% from your clean pressure, then do a standard spray washing off of the carts. If when you do this the pressure does not drop down to your original clean cartridge pressure, then is the time to do the more thorough soak cleaning.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: size of pool - new estimate after shocking

    Make sure you pass all three end of shocking criteria (in my sig) simultaneously. Next time you are uncertain, you can always do the OCLT to check.
    Thank you for the reminder. I did apply the three shocking criteria. Day three, when I decided to end of the process, I was unsure about the results of my OCLT test. The FC reading was hard to decipher because of the paleness of the samples I tested -- super-faint pink or clear? With CC=0 and crystal clear water I decided to stop. Would you suggest another approach for this situation?

    Sounds like you have a reason to adjust, and going lower is safer than going higher. Are you certain you had the right concentration in the poolcalculator.com for the bleach. 8.25% bleach has started to dominate the market.
    Bleach I've been using has been steady at 8.25% or sometimes 8.3%. Could you please explain "lower is safer" -- for what -- for the equipment? My deep fear is that I've been harming my equipment by overdosing, thinking the pool was about 5k larger in volume than it turns out to be. Underdosing is not appealing either for algae reasons. I will just try to maintain the pool using pool calculator assuming volume of 18K for a bit and see how it goes. Sound ok?

    If anyone cares this was the math problem I did to solve for volume:

    815 oz = 626 oz
    _____ ______
    23,000 x

    x= about 17,500


    When your pressure goes up 25% from your clean pressure, then do a standard spray washing off of the carts. If when you do this the pressure does not drop down to your original clean cartridge pressure, then is the time to do the more thorough soak cleaning.
    I am so happy to hear this! Thanks for the specific instructions on when to do the more thorough cleaning!

    ________

    And don't get me wrong! Though I've had a few bumps in the road I feel good about taking care of the pool myself. Thanks for all the advice.

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    linen's Avatar
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    Re: size of pool - new estimate after shocking

    It is unlikely you harmed anything. What i meant by lower is better is that you won't overdose, but you may underdose which is quickly fixed.

    Your math makes sense, and as you continue to dose you may get a better idea of your real volume. Also if you want to post your pools dimensions, we can calculate an estimate.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: size of pool - new estimate after shocking

    Thank you for your reply! Will be back in touch as needed!

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