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Thread: SWG Setting After Shocking...

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    SWG Setting After Shocking...

    Folks,

    So I have a 15K gallon pool and have a bit of an algae problem -- probably due to my SWG clogging up with calcium a bit back and then having things off after that.

    I've noticed that after shocking my pool to get the algae under control, with my SWG set to around 40% (rated for a 40K gallon pool), the chlorine stays very high for days and days.

    Should my procedure be to lower my SWG a lot during those first few days, then raise it back up again? I'm leaving town for a week and have to guess at what to do while I'm away.

    Thanks!

    - Jeff
    15,000 gal SWG pool, cartridge filter, all pentair equipment, variable speed pump, 400K BTU heater and spa, pebbletec finished

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    frustratedpoolmom's Avatar
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    Re: SWG Setting After Shocking...

    You can simply turn the SWG off until the FC drops down to normal range and then turn it back on the desired setting.
    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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    Mod Squad Bama Rambler's Avatar
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    Re: SWG Setting After Shocking...

    Do you normally run your SWG at 40% to maintain the FC at the target level?
    Is it only after shocking that it takes a while for the FC to return to normal with the SWG set to 40%? (I think that's what you meant)
    How are you shocking? (are you using liquid chlorine, Bleach)
    How are you testing the water?
    Can you post a full set of numbers for us? That would help us know what's going on.

    If I understand correctly, I'd just turn the SWG off while shocking and let the FC drift back close to normal then turn the SWG back on and let it maintain the target FC.

    If you don't have a good test kit I'd suggest investing in one. With good testing and control you rarely if ever have to shock.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: SWG Setting After Shocking...

    Quote Originally Posted by Bama Rambler
    Do you normally run your SWG at 40% to maintain the FC at the target level?
    Is it only after shocking that it takes a while for the FC to return to normal with the SWG set to 40%? (I think that's what you meant)
    I'm actually not 100% sure that 40% is the right number for my SWG because what I think happened after the last shocking event (several months ago), I let the pH drift higher and the whole time the SWG was becoming less and less efficient, so I kept bumping it up. Then one day, I noticed that things were not right, checked the SWG to find that the cell was totally calcified. Since then I've been watching my pH better, but I think by then, some algae got a foothold. Nothing serious, just a low grade event.

    Is there a good way to calculate a starting point for my SWG that will be safe and not run my FC too high? I figure if it is rated for 40K gal, then if I have about 15K, I need 35-40% output.

    Quote Originally Posted by Bama Rambler
    How are you shocking? (are you using liquid chlorine, Bleach)
    Bleach, thanks to you guys!

    Quote Originally Posted by Bama Rambler
    How are you testing the water?
    TF-100 kit

    Quote Originally Posted by Bama Rambler
    Can you post a full set of numbers for us? That would help us know what's going on.
    Some of these numbers are a bit older, but I adjusted the pH before adding bleach last night, then scrubbed, etc. Ran the pool all night with the SWG set to 50%. Swept this morning and brushed. Looks decent, but not 100%. FC = 23, CC=0.5 this morning. pH = 7.4

    TA=100, CH=500, CYA=60, temp=83

    Quote Originally Posted by Bama Rambler
    If I understand correctly, I'd just turn the SWG off while shocking and let the FC drift back close to normal then turn the SWG back on and let it maintain the target FC.
    That seems to take days and days, and then I seem to end up setting the SWG too high. This is where I'm struggling to get enough FC, but not run this too hard and have my numbers get too high.

    Thanks for any additional tips!
    15,000 gal SWG pool, cartridge filter, all pentair equipment, variable speed pump, 400K BTU heater and spa, pebbletec finished

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    Mod Squad Bama Rambler's Avatar
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    Re: SWG Setting After Shocking...

    Since I don't have a SWG I'll let someone with more experience give you advice on how they operate it.

    I think I'd set the SWG low and supplement it with bleach while things straighten out.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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