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Thread: FC consumption when closing with Algaecide

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    Join Date
    Jul 2013
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    Staten Island, NY
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    22

    FC consumption when closing with Algaecide

    I believe I've read on the forum that chlorine will break down algaecide (polyquat). When using algaecide during pool closing, won't the pool consume more FC than if you had not used algaecide maybe to the point of total FC consumption well before opening? At the very least, wouldn't the chlorine break down all the algaecide negating any benefit of its use leaving you with much lower levels of FC?

    Last closing was my first and I did use polyquat. I opened to crystal clear water with a residual FC of 2 and no CC. I guess I can just repeat but wanted to educate myself first.

    Thanks,

    Vlad
    12x20x52 AG ~6000 gallons (2ft bury), Waterway PH2100-6 1HP 2 spd pump, Hayward Xtreme 100sqft filter,
    Pool Pilot Digital Nano Plus SWG 5/2014, Hayward Heat Pump HP50HA 8/2014, Wanda the Whale cleaner

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    Join Date
    Jun 2013
    Location
    East TN
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    Re: FC consumption when closing with Algaecide

    Yes, chlorine will break down polyquat and quat algaecides. I believe there is an added benefit of having the polyquat turn into a clarifier when broken down (If I remember right). If you opened to clear water then you done a good job and just repeat. My only suggestion is keep a check on your FC a few times during the closing especially about spring time.
    18,000 Gallon Aboveground. Sand Filter with 2HP 2 speed Pump.

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    Mar 2007
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    San Rafael, CA USA
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    Re: FC consumption when closing with Algaecide

    Buckman Labs says that the Polyquat that is broken down is still effective as an algaecide. Also, if you close the pool with the water temperature cold (50F or below), then the algaecide will last a much longer time even in the presence of chlorine. That's the recommended approach. Basically, at warm pool temperatures in one week the Polyquat might degrade by at about one-third with normal chlorine levels, but at 50F it would take perhaps 5-7 weeks for that same level of degradation to occur. So if you close late enough and open early enough, you could have the algaecide and even the chlorine still have some residual when you open in spring.
    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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    Join Date
    Jul 2013
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    Staten Island, NY
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    22

    Re: FC consumption when closing with Algaecide

    Thanks, chem geek - that's exactly the type of information I was hoping to get!
    12x20x52 AG ~6000 gallons (2ft bury), Waterway PH2100-6 1HP 2 spd pump, Hayward Xtreme 100sqft filter,
    Pool Pilot Digital Nano Plus SWG 5/2014, Hayward Heat Pump HP50HA 8/2014, Wanda the Whale cleaner

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