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Thread: Draining pool water to lower CH

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    Nectarologist's Avatar
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    Draining pool water to lower CH

    Hi. I know I need to drain and refill but my question is how much of the pool can I drain without jeopardizing the liner? It's only a year old & is in fine shape. Not sure if this is the correct forum but it's chem balancing so I figured I'd start here. My water softener broke when I started to fill the pool last year. I have very hard water so the calcium hardness is super high (> 600 if I remember correctly from last season). I replaced the water softener (after the pool was filled). Now I'd like to get the level of CH down. I assume I should do it on a nice sunny day but is that even necessary. Not opening the pool for a while but want to know what to plan for.
    Thanks,
    Chris
    Inground, vinyl liner, 16 x 32 (approx. 21k gallons), roman end w/ bench, 2 Jandy LED lights
    Pump: Jandy Flopro, 1.5 hp Heater: Raypak, 266k btu (P-R266-A-EN-C; nat gas) Filter: Jandy C340 (cartridge filter) Robot: Doheny's Dolphin Discovery

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    Texas Splash's Avatar
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    Re: Draining pool water to lower CH

    Hi Chris. To answer your basic question - If you must drain your vinyl pool, we typically recommend not draining lower than your bottom step or about one foot from the bottom. At the same time, many TFP members live in areas notorious for having hard water like you (i.e. Arizona, Cali, Nevada, etc), with CH levels well-over 700. It just can't be avoided. Aside from water replacement and/or softening treatments, a good thing to watch is your CSI level. By monitoring the trio of pH, TA, and CH, you can adequately manage the CSI to work in your favor. Perhaps something to consider. Have a nice day.
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    duraleigh's Avatar
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    Re: Draining pool water to lower CH

    What is your current CH? I can't think of any reason why a sunny day would have any affect.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Nectarologist's Avatar
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    Re: Draining pool water to lower CH

    I was just thinking in terms of the liner being more flexible in the sun. The last time it was tested it was 650 I think. I'll use the CSI to manage since I'd rather not drain water. But being able to drain to the bottom step is plenty. I guess I was more afraid of the liner pulling or getting air/wrinkles.

    Thanks
    Inground, vinyl liner, 16 x 32 (approx. 21k gallons), roman end w/ bench, 2 Jandy LED lights
    Pump: Jandy Flopro, 1.5 hp Heater: Raypak, 266k btu (P-R266-A-EN-C; nat gas) Filter: Jandy C340 (cartridge filter) Robot: Doheny's Dolphin Discovery

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    Administrator Leebo's Avatar
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    Re: Draining pool water to lower CH

    With a vinyl pool you really don't need to worry much about CSI as your levels need to be WAY off before you worry about things. With a CH of 650 you could benefit from reducing your CH level, however I personally would wait until the Spring thaw before I worry about it at all. Open the pool early (even if you don't use it) and try to "catch" as much of the fresh rain water that you can. This will greatly assist you in lowering your CH levels. Once things warm up some then retest and post you results here. From there we'll assist you further.

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    Richard320's Avatar
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    Re: Draining pool water to lower CH

    Don't you get plenty of rain and snow to dilute things?

    Test your fill water. If it's high in CH, you'll see very little gain by water replacement. If the pool is at 650 and the fill water is at 300, replacing half of it would only lower CH to 475. Snow and rain by comparison are Calcium-free. So if you drained a foot or two out to make room and aimed a snowblower at the pool to bring it back up, you'd see huge reduction in CH. Redirect a raingutter downspout into the pool during a good storm and you can also harvest a lot of water.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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