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Thread: Leaving Spa Cover off after adding chlorine

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    Leaving Spa Cover off after adding chlorine

    How long should I leave the cover off of the spa after adding chlorine to maintain the residual level and how long do I leave it off after shocking?

    Thanks
    Chuck

    385 Gallon Hawkeye Venus Hot Tub
    Pump 1-Pentair 2 Speed 4.2HP
    Pump 2-Pentair 1 Speed 3.0HP
    Balboa O3zone Chip Ozonator

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    Re: Leaving Spa Cover off after adding chlorine

    I didn't think you needed to leave the cover off for any particular length of time. Not clear what the purpose of doing that would be.
    --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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    Re: Leaving Spa Cover off after adding chlorine

    I have been told that when you shock, you should leave the cover off so that the CC's can escape into the air. With the cover on they just oxidize then fall right back into the spa. Not sure if this info is correct.

    Thanks
    Chuck

    385 Gallon Hawkeye Venus Hot Tub
    Pump 1-Pentair 2 Speed 4.2HP
    Pump 2-Pentair 1 Speed 3.0HP
    Balboa O3zone Chip Ozonator

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    polyvue's Avatar
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    Re: Leaving Spa Cover off after adding chlorine

    Quote Originally Posted by watsocl
    I have been told that when you shock, you should leave the cover off so that the CC's can escape into the air. With the cover on they just oxidize then fall right back into the spa. Not sure if this info is correct.

    Thanks
    Volatile outgassing, eh? I think that's sounds reasonable but you'll have to make an appointment with one of our resident chemists if you want a more precise answer! (Sometimes they make housecalls to visit the symbol-challenged!)

    Indoor pools always seem to have issues with accumulation of chlorine byproducts so I've seen suggested here several times that when shocking one should use electric fans to push the miscreant gases outdoors. It would follow then that removing a spa cover could accomplish the same thing. When I shock my pool I don't leave the solar cover in place -- it comes off until the high chlorine level comes down to about 10% of CYA (the CYA level in my pool is typically 50 ppm, so I replace the cover when FC gets down close to 5 ppm.) Solar covers EDITED Scratch that. I meant SPA covers can take more abuse.... END-EDIT can withstand more abuse than a flimsy solar cover but you probably don't want to lose all that heat, right?

    BTW -- Welcome to the forum!

    EDITED 1-31-2010 5:50 pm PST ----- See Above END-EDIT
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    Re: Leaving Spa Cover off after adding chlorine

    Quote Originally Posted by polyvue
    Volatile outgassing, eh? I think that's sounds reasonable but you'll have to make an appointment with one of our resident chemists if you want a more precise answer! (Sometimes they make housecalls to visit the symbol-challenged!)

    Indoor pools always seem to have issues with accumulation of chlorine byproducts so I've seen suggested here several times that when shocking one should use electric fans to push the miscreant gases outdoors. It would follow then that removing a spa cover could accomplish the same thing. When I shock my pool I don't leave the solar cover in place -- it comes off until the high chlorine level comes down to about 10% of CYA (the CYA level in my pool is typically 50 ppm, so I replace the cover when FC gets down close to 5 ppm.) Solar covers can withstand more abuse than a flimsy solar cover but you probably don't want to lose all that heat, right?

    BTW -- Welcome to the forum!

    Yes. Heat loss is definately a concern. So, in your opinion, you should leave the cover off until the FC gets down to around 5ppm or 10% of CYA. OK! Thanks for the info. And thanks for the welcome. Seems to be a wealth of information here.
    Chuck

    385 Gallon Hawkeye Venus Hot Tub
    Pump 1-Pentair 2 Speed 4.2HP
    Pump 2-Pentair 1 Speed 3.0HP
    Balboa O3zone Chip Ozonator

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    Re: Leaving Spa Cover off after adding chlorine

    At hot spa temperatures, most of the oxidation of bather waste should take place within an hour, though you can check the FC and CC levels to be sure (the CC will rise very soon after adding chlorine after a soak, but will then drop along with FC as the bather waste is oxidized). The most important thing is to add enough chlorine -- many people don't add enough. You'll know you are adding enough if you measure at least 1-2 ppm FC before you next soak (the next day). A rough rule-of-thumb applicable when there is no ozonator is that every person-hour of soaking needs around 5 fluid ounces of bleach or 3-1/2 teaspoons of Dichlor or 7 teaspoons of non-chlorine shock (43% MPS).

    If you are using enough chlorine and always maintaining a chlorine residual (except possibly during your soak), then you should not need to shock the spa on a regular basis. I assume you have read the Pool School article on using chlorine in your spa which is otherwise known as the Dichlor-then-bleach method. If you instead use Dichlor-only, then there is more need for shocking and the water won't last less than half as long as when using the Dichlor-then-bleach method.

    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: Leaving Spa Cover off after adding chlorine

    Quote Originally Posted by watsocl
    How long should I leave the cover off of the spa after adding chlorine to maintain the residual level and how long do I leave it off after shocking?

    Thanks
    I always thought the purpose was to help keep the cover's liner from pitting due to the initial heavy concentration of chlorine. (My previous tub's cover did this which caused flakes dropping into the tub)
    Sundance Hot Tub 365 gal, acrylic
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    Northwest Ohio resident

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    Re: Leaving Spa Cover off after adding chlorine

    Quote Originally Posted by chem geek
    At hot spa temperatures, most of the oxidation of bather waste should take place within an hour, though you can check the FC and CC levels to be sure (the CC will rise very soon after adding chlorine after a soak, but will then drop along with FC as the bather waste is oxidized). The most important thing is to add enough chlorine -- many people don't add enough. You'll know you are adding enough if you measure at least 1-2 ppm FC before you next soak (the next day). A rough rule-of-thumb applicable when there is no ozonator is that every person-hour of soaking needs around 5 fluid ounces of bleach or 3-1/2 teaspoons of Dichlor or 7 teaspoons of non-chlorine shock (43% MPS).

    If you are using enough chlorine and always maintaining a chlorine residual (except possibly during your soak), then you should not need to shock the spa on a regular basis. I assume you have read the Pool School article on using chlorine in your spa which is otherwise known as the Dichlor-then-bleach method. If you instead use Dichlor-only, then there is more need for shocking and the water won't last less than half as long as when using the Dichlor-then-bleach method.

    Richard

    Thanks for the reply. I have printed out (couple weeks ago) and refer to Nitro's posting that you refered to. It has been a big help in maintaining my hot tub. Especially getting the TA and Ph right. I flushed and dumped my spa this weekend and am using dichlor until I build up enough CYA to switch to bleach.

    So if I understand you correctly, the cover should stay off not only when I shock but also when I am just adding chlorine to maintain the residual.

    Thanks
    Chuck

    385 Gallon Hawkeye Venus Hot Tub
    Pump 1-Pentair 2 Speed 4.2HP
    Pump 2-Pentair 1 Speed 3.0HP
    Balboa O3zone Chip Ozonator

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    spishex's Avatar
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    Re: Leaving Spa Cover off after adding chlorine

    Quote Originally Posted by BC
    I always thought the purpose was to help keep the cover's liner from pitting due to the initial heavy concentration of chlorine. (My previous tub's cover did this which caused flakes dropping into the tub)
    This usually only happens if you're adding excessive chlorine. Normally when I see a wrinkled cover and ask the owner about how they sanitize it they explain that they add chlorine regularly. Chlorine being 1/2 cup of dichlor at a time, and regularly being once a month. Adding it in small doses every few days keeps the concentration from getting to vinyl-destroying levels. I don't leave covers off for more than about 15 minutes, and that's just the time it takes to clean the tub and inside of the cover.

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    Re: Leaving Spa Cover off after adding chlorine

    I think for normal maintenance doses it is not necessary to leave the cover off--we are talking only a few ppm here. I never have and CC buildup has not been an issue. If you should get into a situation where it is necessary to shock, then it might be worthwhile to leave the cover off.
    --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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    Re: Leaving Spa Cover off after adding chlorine

    I don't know if this will be any help or if I'm actually accomplishing anything. Leaving my cover open for any length of time lets in debris from the trees, flying silt, and bugs (most of the year). When I'm in the tub I can just scoop the stuff out. When not in tub and adding maintenance does I prop one side open a few inches. Otherwise, if making larger adjustments I'll prop it open using a couple of water filled jugs. Out here I have to take notice of wind as when it is propped open, if the wind is strong enough, it will flip the top open and sometimes all the way off.

    That bright thing is the sky just showed itself. What do they call it? Sun???? Boy I like this.

    gg=alice
    1981, 25K, IG, Blue Plaster 1996, somewhat oval, widens a bit at shallow end, 1.5" pipes, 2" at Pad, 1 separate main drain, 1 skimmer, 4 returns + dedicated cleaner return, 10 ft deep end with very fast decline from shallow, Pentair Quad 80 DE, Pentair Intelliflo VF, 3/4 HP Booster Pump (equipment pad about 8 ft below top of pool), Challanger 3/4 Trash/Emergency Pump 120v, Polaris 280 (pressure), iRobot Verro cleaner (robotic), Aquabot Turbo (robotic), Jacuzzi Tracker 4X (vacuum) Pool Blaster (Buster), Two (2) PoolSkims, Solar Breeze (solar powered top skimmer) (beta to ver. 2, release date 2010), ColorSplash LED replacement bulb. Aries 550 gal separate spa, 2002 (our 3rd and BEST spa) , BBB-Bromine

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