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Thread: To Shock or Not to Shock?

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    Join Date
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    To Shock or Not to Shock?

    Background:
    After 20 years of owning my pool and encountering many problems I am now just learning about pool chemistry through this site. I ordered and received a TF-100 test kit and love it.

    While waiting for the TF-100 to arrive I noticed that the top step of my pool ladder had turned pink. I also saw a little pink on the rubber feet of the ladder. When I poured liquid chlorine directly on the top step the pink immediately disappeared, telling me it was probably organic! I pulled the ladder out of the pool and the underside was much worse. I cleaned the ladder with bleach and a brush and put it back in the pool. The pink does not appear to be anywhere else in the pool.

    I now maintain my FC between 5–10 ppm based on my CYA being 60+ ppm. I seem to be losing 4 ppm over a 24 hr period the three times I’ve checked it. I’ve checked the FC loss overnight twice. The first time it was 1 ppm but last night I lost 2.5 ppm. My CC level has maintained at < 0.5.

    I have not yet shocked my pool this summer, because of our short swimming season I hesitate to lose good swimming days to shocking the pool. I am still a little confused about chlorine loss/consumption. I read in “pool school” to expect to lose 2-3 ppm daily and that there should be 0-1 ppm loss overnight.

    My pool water currently looks excellent.

    Questions:
    I’m not sure if the 0-1 ppm overnight loss only applies when you are shocking the pool or also when just maintaining normal levels?

    Given the amount of chlorine loss daily and overnight, do you think I still have a pink slime problem and should shock the pool?

    Shouldn’t my CC be higher if I have a problem?

    Am I just paranoid?
    Roger

    14 x 28 Vinyl Inground, 13200 gal., Hayward EC-65 DE w/1hp Superpump

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    frustratedpoolmom's Avatar
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    Re: To Shock or Not to Shock?

    Your not paranoid. There is a rarer form of algae that is pink.

    You should shock your pool. That much FC loss overnight, shocking or normal levels, indicates algae.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: To Shock or Not to Shock?

    Thanks for the response. I decided to take your advice and shock the pool.

    Twenty-nine hours later and I'm still shocking! I'm beginning to doubt that I know what I'm doing! I'm still not able to maintain my FC level for any length of time and the whole time my CC reading remains at < 0.5.

    My procedure is to dose the pool with the filter running, wait one hour for it to mix and then test. So far I have not attained the level that the pool calculator estimated I would but that could just be that my pool gallon size is off or maybe my sample location is not giving me a representative sample. I'm thinking of pulling two samples from different locations to see if they match. I'm sure it probably didn't help that it poured down rain several times during the process. I actually had to drain water from the pool at one point.

    Any encourgement/advice would be appreciated!
    Roger

    14 x 28 Vinyl Inground, 13200 gal., Hayward EC-65 DE w/1hp Superpump

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    Re: To Shock or Not to Shock?

    Correction to that last post, sorry. I've been shocking the pool for seventeen hours, not twenty-nine. I think I'm sleep deprived!
    Roger

    14 x 28 Vinyl Inground, 13200 gal., Hayward EC-65 DE w/1hp Superpump

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    duraleigh's Avatar
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    Re: To Shock or Not to Shock?

    Chlorine is consumed by two things........

    The 1) sunlight and 2) organics in your pool. It certainly sounds like you have a bunch of organics in your pool and you need more chlorine to kill them.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: To Shock or Not to Shock?

    Chlorine is consumed by two things........

    The 1) sunlight and 2) organics in your pool. It certainly sounds like you have a bunch of organics in your pool and you need more chlorine to kill them.
    Thanks for the reply. As a newbee to pool chemistry I guess it's just a little hard to comprehend that with good FC, low CC and good looking water there is someting bad in there. But I suppose if it (the pink) was growing on the ladder there might still be some somewhere else.

    I suppose I should be brushing the sides of the pool during this whole process!?
    Roger

    14 x 28 Vinyl Inground, 13200 gal., Hayward EC-65 DE w/1hp Superpump

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    frustratedpoolmom's Avatar
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    Re: To Shock or Not to Shock?

    The other thing to consider is your chlorine source? what kind are you using, where did you buy? Do you trust it's strength?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: To Shock or Not to Shock?

    Roger,

    Organics (algae) are easy to confirm. Put some chlorine in your pool after the sun is off it. Test the FC level and record it. Then, get up a little early the next morning and test it again before the sun can burn it off. Put another way, you are testing to see if your pool l;oses any chlorine at night.

    If your tests differ by 1.0 or more, you have organics and high levels of chlorine is the answer.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Lewisberry, PA
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    Re: To Shock or Not to Shock?

    If your tests differ by 1.0 or more, you have organics and high levels of chlorine is the answer.
    Update, I have continued the shocking process and last evening brushed the entire pool. The water looks really excellent and sparkly with nothing dead accumulating on the bottom.

    I did do the overnight chlorine loss test last night and lost 2 ppm so I am continuing the shocking process throughout today and tonight and will vaccum and backwash the filter as well. The CC test is only showing as very light pink and has remained < 0.5 throughout the entire process.

    I sure hope I get good results overnight tonight as I'm missing some really good swimming weather here in the NE.

    PS: I just ordered more reagent for my new test kit, goes pretty fast when your testing such high levels as often as I have been!
    Roger

    14 x 28 Vinyl Inground, 13200 gal., Hayward EC-65 DE w/1hp Superpump

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