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Thread: Shock level questions

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    Shock level questions

    I have a saltwater pool, and I accidentally let my FC fall too low and now I have an algae problem. Even though my OCLT only lost 1ppm and my CC is 0.5 I have algae. My question is looking at the pool calculator, it says to raise it to 21ppm to shock, but looking at the chlorine/cya chart it says I need to be at a level of 30ppm to shock. Which one is correct if my CYA is 80?
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Butterfly's Avatar
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    Re: Shock level questions

    Both shock levels will work. The CYA/Chlorine chart shock levels are more agressive than the PoolCalculator shock levels.

    I normally recommend the higher shock levels.
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    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: Shock level questions

    Only had enough bleach to get it up to 23.5ppm so I hope that will be enough tonight until I can go get some more bleach in the morning. It isn't losing more than the 1ppm in the OCLT, but there was plenty of green stuff on the floors and walls when I vacuumed today.
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    Mod Squad Bama Rambler's Avatar
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    Re: Shock level questions

    Just hold shock level until you pass all 3 criteria. Both BF and myself have them listed in our sigs.
    Dave J. TFP Moderator
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    Re: Shock level questions

    Thanks for your replies!! I never failed the first two criteria but the last was something else. I have never been able to vacuum my pool until recently because of a cracked skimmer. Still not 100% but I am somewhat able to vacuum. I brushed the pool and the stuff that came up was green looking and I could see very clearly where I had and hadn't brushed. A couple of days later I got a vacuum head and when I started I could see green algae growing in places on the walls and floor. I vacuumed the best I could and the water turned VERY cloudy. It is looking better today after bringing it to shock level last night, and I've been adding DE to the filter after every backwash. Reason my FC fell is my SWG is going out I believe. I have a Polaris Autoclear Plus and it is not keeping up due to I believe the cell being 6-7 years old and FC falling over time. I am having to add bleach when it calls for it. Don't have the money to replace the SWG right now so I am having to make do.
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Re: Shock level questions

    Wow! The OCLT showed that I was ok as I only lost 1ppm. Level was at 28.5ppm this morning when I checked it and left for work. When I returned home from work I checked again and it had dropped to 13ppm. It lost 15.5ppm in just around 7 hours today. Could this be from the sunlight or does this prove that algae is still alive and well? My CYA is at 80. I am pretty sure my SWG isn't doing hardly anything but I am compensating with bleach. Water is definitely clearing up.
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    frogabog's Avatar
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    Re: Shock level questions

    Let your SWG rest while you're shocking, especially if you need to replace the cell. Might be a good time to clean it real good as well.

    And yes, it sounds like the chlorine you added is busy murdering algae. Keep it going, maintain. Maybe raise it a bit above shock level if you can't be around all day to check and maintain it. See what you're loosing this evening in the hourly tests and guestimate what you might loose tomorrow while gone, add that much extra. You may want to raise it a little above shock tonight while you sleep as well.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Re: Shock level questions

    Raised the level to 33-34ppm tonight before I go to bed and will check in the morning. A question I have is with no algae and a cya of 80, how much FC will I lose with 95+ degree day with pool in direct light and the SWG unplugged just using bleach? As soon as I get this algae under control I am going to add borates and work on getting a working SWG.
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    frogabog's Avatar
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    Re: Shock level questions

    Well, you do have algae so it'll be hard to quantify it for you. Sounds like you'll be ok with the amount you added, when you test after work you'll have the answer to that question. If you don't fall below shock level, once your pool is out of the sun you'll be able to see what you're loosing every hour. It should become less and less as time goes on.
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
    Don't waste time and energy looking for a better value on test kits, the TF100 is the best deal around. I did the looking and spent the extra money, but you don't have to make the same mistake. Just go here: TFTestkits. I use Pool Calculator for min/max, and shocking chlorine levels.

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    Mod Squad zea3's Avatar
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    Re: Shock level questions

    Since you have a vinyl liner do not raise the FC more than a couple of ppm above shock level. 33 ppm should be ok but I would not raise it higher for an extended period of time or you risk bleaching the liner. The higher your FC is the quicker it will drop. Since you are not able to bump it back to shock level several times during the day, bring the pool to shock level before you go to work, when you get home, and just after sundown. When the water is clear you can run the the overnight test to see if you are finished with the shock process.
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    Re: Shock level questions

    Checked it this morning and it was 29.5ppm down from 33.5ppm from when I went to bed. It was storming also last night. Water is pretty clear this morning as well. I will keep it around 30ppm today to keep from bleaching the new liner out.
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Re: Shock level questions

    Just check the levels again and from 7:30 this morning until 11 it went from 29.5ppm to 27.5ppm and it is cloudy here. How much can I expect to burn off during the day with everything fine ie no algae, levels correct, ect? I read where it will burn off at a higher rate with higher levels.
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    Butterfly's Avatar
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    Re: Shock level questions

    Quote Originally Posted by jsw5620
    ..... How much can I expect to burn off during the day with everything fine ie no algae, levels correct, ect? I read where it will burn off at a higher rate with higher levels.
    Well, try this info on the FC burn-off rate:
    question-about-daytime-fc-loss-t12839.html

    hth
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  14. Back To Top    #14

    Re: Shock level questions

    Quote Originally Posted by Butterfly
    Quote Originally Posted by jsw5620
    ..... How much can I expect to burn off during the day with everything fine ie no algae, levels correct, ect? I read where it will burn off at a higher rate with higher levels.
    Well, try this info on the FC burn-off rate:
    question-about-daytime-fc-loss-t12839.html

    hth
    Thanks!
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Re: Shock level questions

    Just retested again. At 11 it dropped to 27.5 so I added 182oz of bleach which should have brought it to 30.6. At 2:30 it dropped to 24 so that is roughly 6.5ppm in 3.5 hours. I am going to add 364oz of bleach now to bring it back up to 30ppm.
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Re: Shock level questions

    From 8pm last night until 7:30 this morning FC went from 30 to 29.5!!!
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

  17. Back To Top    #17
    Butterfly's Avatar
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    Re: Shock level questions

    You're getting there!
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  18. Back To Top    #18
    Mod Squad Bama Rambler's Avatar
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    Re: Shock level questions


    Winning the battle!
    Dave J. TFP Moderator
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  19. Back To Top    #19

    Re: Shock level questions

    Just tested again. I went from 29.5 to 23 from 7:30 to 10:30. Could that be from normal burn off from sun (SWG is turned off)? Since I passed the OCLT and my water is clear, do I let it fall back to normal levels now?
    31,000G IG vinyl 20X40 True L. Hayward 1.5 superpump, Autopilot Pool Pilot Digital SWG, Hayward Model S244T 300lb sand filter, TF100 kit

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    Ohm_Boy's Avatar
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    Re: Shock level questions

    When you do your overnight loss tests, the SWG is OFF, right?
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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