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Thread: water level in a closed pool

  1. #1
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    water level in a closed pool

    Am I correct that the water level is a non-issue until you get freezing temperatures?

    My safety cover w anchors allows rain water to go right in & re-fill the pool.

    The reason I ask is because I have lowered the water level 4 inches below the returns and we will not get freezing temperatures until December or January and even then only very rarely. If I can avoid lowering the water level until we get closer to freezing temperatures that will be less labor . Or are there other good reasons (chemistry, plasters line/stain etc.) to keep this water level.
    I did not blow out nor did I plug the lines because they will just drain once the water level is lowered, everyone in Charlotte assures me this is okay.
    Thanks
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  2. #2
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    Re: water level in a closed pool

    Yes, water level in the pool matters.

    If the water table outside the pool goes higher then the water level in the pool, uplifting pressures will be exerted.

    Liners will float and not set correctly resulting in wrinkles, tears, reduced life.

    Fiberglass and concrete pools can lift up out of the ground, tearing plumbing & concrete, form cracks in decking, etc...

    Pools with a tile line should have an automatic step pump placed to keep water just below the tile line. This will help prevent cracking when ice expands against them.


    Scott
    PoolGuyNJ
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  3. #3
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    Re: water level in a closed pool

    [quote="PoolGuyNJ"]Yes, water level in the pool matters.

    If the water table outside the pool goes higher then the water level in the pool, uplifting pressures will be exerted.
    Fiberglass and concrete pools can lift up out of the ground, tearing plumbing & concrete, form cracks in decking, etc...


    Thanks. How does one know the water table outside? Sorry I don't understand this too well. And I'll recheck PoolSchool on this too.
    How about my question re water level being irrelevant till a freeze; I absolutely will keep it below tile line reguadless of temp.
    Thanks again.
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

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    Re: water level in a closed pool

    I like to encourage my customers to use an automatic step pump to handle this situation. I usually sell the Little Giant 500APCP. It's plastic body doesn't harm plaster finishes and is low profile so it doesn't rub against the bottom of the cover except with extreme snow loads.

    I like to set them on the step of the deep end swim out if a pool has one. This step is usually an inch or so lower than the 1st step in the shallow end. If the swimout either doesn't exist or has no step, then the second step on the shallow end sitting on a couple bricks to bring it up a couple inches higher but lower than the 1st step. This usually keeps the water below the tile.

    Once the pool's surface has a 1/2" inch of ice formed and it's expected to stay that way, unplug it. The discharge hose will probably be frozen up and the pump will just dead head. If practical, plug it in near the back door closest to the house. This way, if the GFCI trips, it's a short walk.

    Run the discharge hose down hill and away from the house. Avoid the driveway. If ice forms overnight on a wet driveway, you have a problem. Flag it with landscape flags so the landscapers don't run over it with a lawn mower.

    Hope this helps.

    Scott
    PoolGuyNJ

    PS: The Little Giant part number is 519575
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  5. #5
    Senior Member spishex's Avatar
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    Re: water level in a closed pool

    It isn't often that we see ice on the surface for extended amounts of time around here. You'll probably be able to just leave the pump in place. But that's what I'd recommend as well.

    There aren't many cases in our area where I drain a pool that low, and it's always to do with below grade equipment. We only have a 12" frost line which in most cases is just above the bottom of the skimmer and well above any plumbing lines (assuming they were installed correctly). That's why they said plugs weren't necessary. However, if you've got it drained to that level you may as well plug the empty lines.

    The other issue for your plaster is calcium saturation. Depending on how much rain we get, your water is going to be slowly diluted and your CSI will decrease. If you were only in the 250-300ppm range to start with, you may need to add some calcium at some point.

  6. #6
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    Re: water level in a closed pool

    spishex,
    Thanks so much. It is very helpful to have a local expert. This is my 1st year of pool care.

    Quote Originally Posted by spishex
    It isn't often that we see ice on the surface for extended amounts of time around here. You'll probably be able to just leave the pump in place. But that's what I'd recommend as well.

    There aren't many cases in our area where I drain a pool that low, and it's always to do with below grade equipment.
    My equipment is fine. So next year, just draining 2-4 inches below the skimmer is good? Where do you lower the water level to?
    We only have a 12" frost line which in most cases is just above the bottom of the skimmer and well above any plumbing lines (assuming they were installed correctly).
    "the bottom of the skimmer" means? The bottom of the square hole on the wall where the water enters when a pool is open? Or the bottom of the cylindar the skimmer basket sits it?

    Also, what exactly is a frost line? The dirt deeper than 12" won't freeze solid? And we can relate this to open water in a pool how?

    If you had my current situation, you'd plug the lines since they are drained. And you'd let the water level rise from the rainfall untill it gets 2-4inches from the skimmer (or however you answer me above), or would you maintain the water level I closed at (3-4 inches below teh Returns). Next year I'll get it right.

    That's why they said plugs weren't necessary. However, if you've got it drained to that level you may as well plug the empty lines.
    OK I will, thanks for suggestiong that.

    The other issue for your plaster is calcium saturation. Depending on how much rain we get, your water is going to be slowly diluted and your CSI will decrease. If you were only in the 250-300ppm range to start with, you may need to add some calcium at some point.
    On 8/23/09, my CH was 370-380; I closed about 10/17/09. You think I'll be OK or when should I test it this winter?
    Again, I really appreciate your & everyone's help
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  7. #7
    Senior Member spishex's Avatar
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    Re: water level in a closed pool

    My equipment is fine. So next year, just draining 2-4 inches below the skimmer is good? Where do you lower the water level to?
    I'd drain your pool to below the tile line, assuming you have tile, plus a few inches since you have a mesh cover and water will come in. You want to keep it just below the tile, which can be tricky with a mesh cover. That's why Scott above recommends a sump pump on the step which is the easiest way to take care of water over the winter.

    "the bottom of the skimmer" means? The bottom of the square hole on the wall where the water enters when a pool is open? Or the bottom of the cylindar the skimmer basket sits it?
    Also, what exactly is a frost line? The dirt deeper than 12" won't freeze solid? And we can relate this to open water in a pool how? If you had my current situation, you'd plug the lines since they are drained. And you'd let the water level rise from the rainfall untill it gets 2-4inches from the skimmer (or however you answer me above), or would you maintain the water level I closed at (3-4 inches below teh Returns). Next year I'll get it right.


    The bottom of the skimmer being below the mouth of the skimmer, so no water from the body of the pool is entering the skimmer. You can use a gizzmo or closed cell foam to protect the skimmer body.
    The frost line is the depth at which water in the soil can be expected to freeze. That relates to your pool because of the depth of your plumbing. If your equipment is above ground, and all your plumbing is more than 12" below ground (which it is supposed to be) then there's no danger of pipes freezing because they're essentially insulated by the ground. It doesn't hurt to blow the lines out, especially if you're not sure about their depth, but in most cases in our climate you can get away with not doing it. You still need to blow out all the lines above ground.
    In your case I'd plug the returns (since it would be a shame to already have them empty and let them fill back up) and let the water come back up. Where to? Below the tile, but as far up as you can conveniently place a pump. Probably on the top step.

    On 8/23/09, my CH was 370-380; I closed about 10/17/09. You think I'll be OK or when should I test it this winter?
    Depends on the amount of water left in the pool, the amount that will be added and the CH of the water that will be added. With rain I assume the CH will be 0, but I've never checked. That would make your calculation easier. If you drained more than about 1/4 of the pool you may need to add more as the water level rises.


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    Re: water level in a closed pool

    Quote Originally Posted by spishex
    With rain I assume the CH will be 0, but I've never checked.
    Well, uh, not that I was, you know, excited about the new test kit last winter, or looking for any excuse to try things out, or anything, but (ahem) I have tested rainwater... TA and CH of my rainwater sample were both undetectable with the Taylor tests. (And pH below 6.8.)
    --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
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  9. #9
    Senior Member spishex's Avatar
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    Re: water level in a closed pool

    Quote Originally Posted by PaulR
    Quote Originally Posted by spishex
    With rain I assume the CH will be 0, but I've never checked.
    Well, uh, not that I was, you know, excited about the new test kit last winter, or looking for any excuse to try things out, or anything, but (ahem) I have tested rainwater... TA and CH of my rainwater sample were both undetectable with the Taylor tests. (And pH below 6.8.)
    --paulr
    Nerd!

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    Re: water level in a closed pool

    I understand now.
    It is true that we rarely get ice for extended periods of time & most likely the pool water has never had the surface freeze (but I’ll be checking from now on, this is my 1st year of pool care; I know the water in the skimmer housing froze & I learned how to solved that).

    My pump will rest on the 2nd step because the ideal winter water level for me is half way between the 1st & 2nd steps. Final questions (I hope). When it gets to freezing temps, I must remove the pump because it’ll freeze & break, or just remove the pump when/if I see the surface frozen? If the water surface isn’t frozen then I can leave the pump on the step, right? I’m trying to preserve my pump & not ruin it the 1st year.

    FWIW:
    Spishex, who is in my area, mentioned that I need not lower my water level “below the Returns”. I originally planned to lower it 2-4 inches “below the Skimmer” as spishex mentioned, but chose “below the Returns” instead because I have:
    - two Jets, 2.5 inches below the skimmer/tile line
    - a Pool Cleaner 3.5 inches below the skimmer/tile line
    And I didn’t want to fiddle with such precision of the water level re the above Jets & Cleaner because
    -From Bottom of Skimmer to Returns is 5 ½ inches, so below the Returns was a simpler level to maintain. I don’t have an “automatic” pump, just the other kind that you must monitor or it’ll break.
    Nevertheless, 2-4 inches below the skimmer is what I have settled on, I’ll risk the Jets & Cleaner line I suppose. Should be no “risking” if I get an automatic pump which I plan to do. But I really don’t look forward to placing & removing this pump every time we get close to freezing - that’s why I ask about it.
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  11. #11
    Senior Member Thinkly's Avatar
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    Re: water level in a closed pool

    So can water level effect things like return plugs, lights and or the skimmer opening in a fiberglass pool? IOW, will the frozed ice damage the things i mentioned?
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

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    Re: water level in a closed pool

    If your skimmer is plugged with an ice compensation device such as a gizmo or blow through extension or even a gallon jug that is half filled with pool antifreeze, its fine. Plugs in the lines are uneffected as are lights. They are normally below the frost line and the water is still liquid. Pools don't normally freeze all the way through. If you live in Alaska, Northern Idaho, Montana, North Dakota, or Northern Wisconsin, your mileage may vary.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  13. #13
    Senior Member Thinkly's Avatar
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    Re: water level in a closed pool

    My skimmer has a jalf full jug of antifreeze in it. I'm not concerned about the skimmer body i was more concerned about the opening and the plugs where a sheet of ice may form, expand, possibly shift and break the plastic around the skimmer opening or the plugs and there fittings.
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Re: water level in a closed pool

    1st pool closing, huh?

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  15. #15
    Senior Member Thinkly's Avatar
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    Re: water level in a closed pool

    You guessed it.

    Regardless i guess i never got an answer. Can surface ice cause damage to items that it intersects within the pool?
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

  16. #16
    Senior Member Thinkly's Avatar
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    Re: water level in a closed pool

    anyone?
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

  17. #17
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    Re: water level in a closed pool

    Quote Originally Posted by Thinkly
    You guessed it.

    Regardless i guess i never got an answer. Can surface ice cause damage to items that it intersects within the pool?
    [EDIT] Thinkly, I see you are in NC Kansas. I'm pretty sure you are in a colder zone than in NC Texas and NC so you'd best wait for one of our Northerners to answer that. At least this post will bump your question up. [end edit]

    I've never had any freezing damage in the main part of pool, in 23 years, and I never drain, usually keep open all year. A couple of years in past 23 years we did get ice, about 1/4" in pool. I didn't have anything lowered but did put jugs in the skimmer and pool. One winter, we had temps that hovered around 0 F for a few days. My pump station is below grade but I did have one of my 1.5" pipes freeze coming out from the ground to the pump station. After that I started putting freeze tape and insulation on the pipes when I did have to empty everything else at pump station. We had 23 F last night with temps hovering around 32 F all day. (I have some beautiful ice sculptures around the spicketts that are open a bit and dripping. ) Pump was off from 1000 to 1630 so no water moving. Tonight is predicted to 22 F. My pool water is hovering around 40. Even when the temps were so low those rare winters, I didn't have any plastic cracking at the rim of skimmer where it meets concrete. But interestingly enough as I was backwashing tonight (thank goodness no wind for a change) I was thinking about the very thing.

    I do think those in the upper states can best guide us about that. So I'm sure someone will come along.

    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

  18. #18
    Senior Member polyvue's Avatar
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    Re: water level in a closed pool

    I lived in Kansas City for several years so feel qualified to answer this question based on how cold I know it can get at this relatively southern latitude in the mid-west. Certainly ice sheets can and do cause damage to non-masonry pool parts during the winter thaw-freeze cycles. However, members on the East coast, from what I've read here, typically use a milk jug in skimmers that are presumably not fully drained. In several threads I've noted, members have inserted a gizmo into the drain plug in the skimmer -- to prevent water from entering and/or antifreeze from exiting the pipes. If this doesn't address your concern, please rephrase with the most specificity you can muster so others will be able to answer.
    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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  19. #19
    Senior Member reindeerboy's Avatar
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    Re: water level in a closed pool

    OK, I have to mention a few things here that I do. I live in North Dakota.

    Right now its 20 below zero out. Thats cold Folks!

    What I do is definitely blow out the lines and put RV antifreeze in them. About 4 gallons. I then plug the lines with my rubber gizmos. I find that these things flex a bit with the ice that forms in the pool. I have a mesh cover as well so what I did was drain the water 20 inches from the top. Then during the fall it does rain some and by the time it freezes the water level comes to about 17-18 inches from the top. The manufacturer of the mesh cover states to not have it below this or the mesh cover will snap if enough snow is on it.

    At about 18 inches, thats about 5 inches below the skimmer cover. Ice does expand up in your pool and up here, it does freeze about 1 foot down. This leaves plenty of expansion. I then put a jug half full of antifreeze in the skimmer. That too has a gizmo in it with a little antifreeze at the bottom to insur no cracking from any moisture/rain that got in there this fall.

    I have had this pool about 4 years now and have had no problems with expansion or cracking in the pool. The biggest issue is to be sure the snow doesnt snap the brass anchors in the cement from the weight on the cover. That happened to me last year when we had 100" of snow. This year has been better so far, thank god! I also plan to keep the cover snow free this year if possible. Even with all that snow last year, I have had no problems with anything upon this springs opening. The only issue was that the water was getting close to going into the skimmer this spring. Within a half an inch so that is why I now monitor the level of the water level in the pool more closely in the fall and drain accordingly as I stated above.

    The ground water table is definitely something to pay attention to. I have a sump pump inside and oustide the foundation of my home so that really makes a difference. It is all plumbed into the waste line and drains properly to the back yard alley (about 50' from the house) so that during the spring it doesnt freeze the 1 1/2" pipe line back up.

    So far, it has worked great. Pic of my pool are in my signature.

    Hope this helps.

    Brrrr its cold out right now. Just let the dogs out to take a leak and man, they didnt stay out long!

    Have a geat xmas everyone!
    Chad R.

    POOL SIZE: 16 x 32' Vinyl lined pool. 22,000 gallons. 8' deep. 2009 Hayward 1.5 HP Super Pump. Hayward S310S 30" 500 lb Sand filter. 1 skimmer and 2 returns. Solar Blanket.

    Pics of my pool: http://s307.photobucket.com/albums/nn312/reindeerboy/

  20. #20
    Senior Member polyvue's Avatar
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    Re: water level in a closed pool

    Hey Chad,

    Thanks so much for posting a great summary of what you do to prevent damage. It answers several questions I had in my mind regarding this process (esp. regarding mesh covers and pool level.) Though you don't mention this, can I assume you remove the pool skimmer's weir as part of your shut-down? BTW, nice topiary near the shallow-end of your pool... I take it that you have to trim the shrub every season to effect that spiral growth (?)

    - Greg
    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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