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Thread: High CH after shocking

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    Aug 2009
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    High CH after shocking

    Hi. I'm new to the forum, but have been reading all the good information here for a couple of weeks. This is definately the best site I've seen.

    We've had our pool a little less than 2 years, and for most of the last year have been fighting patches of algae in the pool. The water was never green, but just couldn't ever permanently get rid of small numerous green algae patches around the sides and bottom, and particularly around the rock feature. I now realize the problem was that all our attempts at shocking the pool were insufficient. I shocked the pool over the last week based on the advice here, and it looks good now. Before shocking:
    FC = 0, CC = .5, CYA = 50, pH = 7.8, TA = 80, didn't measure CH

    After shocking
    FC = 3.5, CC = 0, CYA = 40-50 (hard to tell), pH = 7.2, TA = 100, CH = 620

    I plan to raise the pH to about 7.5, but obviously the problem is the super high CH.

    I have read through the pool school and have decided that the BBB is the way to go but for the recent shock mostly used Leslie's Power Powder Plus since it didn't seem to have a stabilizer in it and I had already purchased it. Bad decision. In hindsight I'm sure this plus all the earlier shock attempts using the same product really raised the CH.

    Is there any other solution other than significantly draining the pool? Is there any other way to soften the water? So far there has not been a problem with any scaling. Will it take a while before this will effect pool equipment? I'm wondering if I can let it lower over time as we get rainfall.

    I checked my local water supply and the CH is about 150 ppm.

    Thanks for any advice.
    15000 gallon gunite pool with smart brite quartz, 2.5 hp pump, Hayward filter, elevated spa, waterfall, smart vac viper pool cleaner

  2. Back To Top    #2

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    Re: High CH after shocking

    Welcome to TFP

    You can use The Pool Calculator to calculate the saturation index. With your numbers and assuming a water temp of 85F I get a saturation index of around 0. If you raise your pH to 7.5, then the saturation index will be +0.3. That's not terrible, but I would suggest that you first lower your Total Alkalinity (TA) level a bit down to 80 ppm or so (70 would be OK too). You can do this through a combination of aeration and acid addition as described in Lower Total Alkalinity. This lower TA will help you keep the pH from rising as quickly.

    I think your pool will be fine even with the elevated CH level. Yes, it will get diluted over time if you have rain overflow of the pool water. Note, however, that evaporation and refill will only increase the CH level as it adds whatever is in the fill water to the pool.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: High CH after shocking

    High CH can be managed, mainly you want your pH to stay in the 7.2-7.5 range. A lower TA will help, as Richard said.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Houston, TX
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    Re: High CH after shocking

    Thank you for the advice. I will use our waterfall and a couple of side jets and see how well that works. I'm sure that we can get some friends over and have even more kids splash in it too!

    The comment about evaporation and refill only adding to the problem is a good one. Eventually maybe a partial pool refill is still something to consider.

    Thanks again.
    15000 gallon gunite pool with smart brite quartz, 2.5 hp pump, Hayward filter, elevated spa, waterfall, smart vac viper pool cleaner

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    Re: High CH after shocking

    In a really active pool with kids, the splashout is pretty significant.

    Because your CH is not outrageous, I agree with Paul and Richard that you can control it with careful pH management and letting the splashout work.

    A partial drain would obviously fix it much quicker but it's not badly broken.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: High CH after shocking

    Houston gets 55 inches of rain a year, in a normal year. We had been low recently but the afternoon thunderstorms are getting back on track so it is not unusual to get an inch of rain in a single day. You never know when a hurricane or tropical storm will drop in and give us 8 inches in a single day.

    I suggest just monitoring the CH monthly.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

  7. Back To Top    #7

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    Re: High CH after shocking

    Part of the High CH is due to using Leslie's Power Powder Plus. It is 73% Cal-Hypo.
    24'x4' AGP Round
    S166T Hayward Sand Filter
    S48K2A2 Hayward Pump

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    Re: High CH after shocking

    Yes - I don't plan on using the Leslie's Power Powder plus again.

    Hopefully the rain we had today made a slight difference- we may have gotten an inch. I will continue to monitor and work on raising the pH so the TA can be lowered.

    With the good advice here I feel better about making this work without draining the pool. Thanks.
    15000 gallon gunite pool with smart brite quartz, 2.5 hp pump, Hayward filter, elevated spa, waterfall, smart vac viper pool cleaner

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    Re: High CH after shocking

    I will continue to monitor and work on raising the pH so the TA can be lowered.
    I suggest leaving your pH alone. It's fine right where it is.

    Lowering the TA may be helpful (lowered thru aeration/acid) but I see no real reason to mess with the pH.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  10. Back To Top    #10

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    Re: High CH after shocking

    I see what you mean.

    I didn't say it right. I really want to lower the TA. Thanks.
    15000 gallon gunite pool with smart brite quartz, 2.5 hp pump, Hayward filter, elevated spa, waterfall, smart vac viper pool cleaner

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