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Thread: Pool level going down

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    Pool level going down

    Good morning,

    After months of investigation and trying to figure out what is going on, I decided to ask for some help on the forum.

    Let's start with the setup:

    - 12,000 gallons pool + higher spa (spillover)
    - 1 3/4HP main pump
    - 1 3/4HP booster for waterfalls
    Most of the equipment are Hayward

    The pool level is going down (between 1 and 2 inches a week) ONLY when the main pump is running. I had a pool company to come out and to test the piping. They told me that all the lines held pressure so I wasted $440. They also dye tested the pool and they found no leak at all. The shell is in good condition and there is no crack.

    The neighbors complained that their grass is soaked on the side of my house and I noticed that the front yard is always wet even though it doesn't rain. Also checked the sprinkler system just in case and there is no leak.

    I am out of ideas so I am reaching out to you to see if anyone had the same problem.

    I hope ya'll can help me !

    Thank you in advance !
    G

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    Re: Pool level going down

    Do you have a multi-port valve on your filter or a push-pull?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pool level going down

    Have you done a bucket test to make sure it isn't evaporation? Put a rock in a 5 gal bucket, put it on a step in the pool and fill it to the pool water level. Check it over a few days to a week to see how the bucket water level compares to the pool water level.

    If the bucket test show there is a leak then one option is to let the water level drop until it stops and that will show you where the leak is. But, be careful if you are in an area with a high water table, empty pools can move or raise up out of the ground.

    We have several areas on our property that seep water for weeks/months after rain. With the drought the last few years those mostly stopped flowing. They started up again this year after the record rainfall we have received.

    Also, here is an article from Pool School about leaks, Pool School - Leak Detection
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    Re: Pool level going down

    Quote Originally Posted by duraleigh View Post
    Do you have a multi-port valve on your filter or a push-pull?
    No I don't. Are you talking about the add-on that allows to backwash the filter ?

    - - - Updated - - -

    Quote Originally Posted by pooldv View Post
    Have you done a bucket test to make sure it isn't evaporation? Put a rock in a 5 gal bucket, put it on a step in the pool and fill it to the pool water level. Check it over a few days to a week to see how the bucket water level compares to the pool water level.

    If the bucket test show there is a leak then one option is to let the water level drop until it stops and that will show you where the leak is. But, be careful if you are in an area with a high water table, empty pools can move or raise up out of the ground.

    We have several areas on our property that seep water for weeks/months after rain. With the drought the last few years those mostly stopped flowing. They started up again this year after the record rainfall we have received.

    Also, here is an article from Pool School about leaks, Pool School - Leak Detection
    The pool company told me to do the test but only for 24 hours. I did not notice a big difference (maybe 1/8" a day). But the thing is I do not lose any water when the pump is off.

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    Mod Squad pooldv's Avatar
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    Re: Pool level going down

    Interesting, that is why Dave's line of questioning is going that way. Do you have a cartridge, sand or DE filter? Sounds like you have a cartridge filter.

    Adding your pool info to your signature will help us to help you better. More here, Pool School - Read This BEFORE You Post
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Pool level going down

    It is a cartridge filter. I just updated the signature. Not sure about the type of pool but it looks like concrete but it is softer
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    I was thinking you may have a leak at the valve (fairly common) but if you have a cartridge filter and no valve, that eliminates that.

    Is any of the decking around the pool settled? That might indicate a cracked pipe underneath the concrete but surely the leak detection company would have explored that.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pool level going down

    Quote Originally Posted by duraleigh View Post
    I was thinking you may have a leak at the valve (fairly common) but if you have a cartridge filter and no valve, that eliminates that.

    Is any of the decking around the pool settled? That might indicate a cracked pipe underneath the concrete but surely the leak detection company would have explored that.
    Well, to them there is no leaking pipe anywhere but that is the only explanation I have since the level is not moving when the pump is off. I guess I will keep the pump running until the leak stops if it does.
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    I guess I will keep the pump running until the leak stops if it does.
    That won't help. If the pump is forcing water out, it will simply suck air when it gets below the skimmers or, if you can exclusively suck water from the main drain only, it will eventually drain your pool.

    If it only leaks "pump on", then the leak is somewhere between the pump and the returns to the pool. Most of that is underground pipe and I suspect that is where the leak is.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pool level going down

    Quote Originally Posted by duraleigh View Post
    That won't help. If the pump is forcing water out, it will simply suck air when it gets below the skimmers or, if you can exclusively suck water from the main drain only, it will eventually drain your pool.

    If it only leaks "pump on", then the leak is somewhere between the pump and the returns to the pool. Most of that is underground pipe and I suspect that is where the leak is.
    Even though the pool company told me that all the return lines held pressure ? Could they have made a mistake ?
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    How did they test the lines? Water? Air? What pressure did it hold and for how long? I would ask those questions and be sure they are confident that pressure was high enough and was held long enough then watched closely enough to detect even a small leak. Testing with water would show a leak quicker than if it was tested with air.
    16' x 32' (21100 gal), vinyl, 1.5 hp Hayward SuperPump,
    Tagelus TA60/60D Sand Filter, Raypak 399K Digital Heater, TF-100

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    Re: Pool level going down

    Even though the pool company told me that all the return lines held pressure ?
    I am simply eliminating the places it can't be.....the places where there is no pump pressure. There is no pump pressure in your pool body nor in the suction lines. It is pretty safe to assume your visible pressure lines, filter, etc have no leaks because you could see it.

    The only place logically left is your underground pressure pipes.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pool level going down

    Quote Originally Posted by Pool Tool View Post
    How did they test the lines? Water? Air? What pressure did it hold and for how long? I would ask those questions and be sure they are confident that pressure was high enough and was held long enough then watched closely enough to detect even a small leak. Testing with water would show a leak quicker than if it was tested with air.
    I believe it was air. I do not have the report with me but I will take a look tonight. I was not with them when they did it but I remember seeing 18PSI on the report.

    *** UPDATE ***

    I called them and they told me they use air (around 17PSI) for about 10/15 minutes.
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    Air is less than ideal, but pretty common. PVC will withstand a high pressure, so presuming they are within the limits of their test plugs they should be able to go to a higher pressure, say 25 or 30 and retest. Then leave the test on longer, maybe 30 mins or better an hour.

    Dave is right in his method of eliminating all the places it can't be. Knowing what you know, the return lines seem suspect.
    16' x 32' (21100 gal), vinyl, 1.5 hp Hayward SuperPump,
    Tagelus TA60/60D Sand Filter, Raypak 399K Digital Heater, TF-100

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    Re: Pool level going down

    I'm probably way wrong, but since you have Hayward products maybe your main drain has the built in hydrostatic valve assembly. There was a thread a little while back. If the pump is on, the suction pulls the valve up (you would think it would be like a suction effect from ground water, but if your soil drains well could possibly leak due to atmosphere pressure pushing on water. After the pump is off the valve is closing back up. Air pressure test would not show this I think
    15x54 swim & play vinyl metal wall AG
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    Re: Pool level going down

    Quote Originally Posted by banditig View Post
    I'm probably way wrong, but since you have Hayward products maybe your main drain has the built in hydrostatic valve assembly. There was a thread a little while back. If the pump is on, the suction pulls the valve up (you would think it would be like a suction effect from ground water, but if your soil drains well could possibly leak due to atmosphere pressure pushing on water. After the pump is off the valve is closing back up. Air pressure test would not show this I think
    Are you saying that the hydrostatic valve could be damaged ? In that case the pool would leak whether the pump is running or not, correct ?

    - - - Updated - - -

    Quote Originally Posted by Pool Tool View Post
    Air is less than ideal, but pretty common. PVC will withstand a high pressure, so presuming they are within the limits of their test plugs they should be able to go to a higher pressure, say 25 or 30 and retest. Then leave the test on longer, maybe 30 mins or better an hour.

    Dave is right in his method of eliminating all the places it can't be. Knowing what you know, the return lines seem suspect.
    I'm going to try the bucket test again tomorrow. I completely shut down the spa to isolate it from the test.
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    Any luck finding cause of problem?
    15x54 swim & play vinyl metal wall AG
    Hayward S210T sand filter 1.5 HP Pentair Superflo vs
    Rheem raypak 130,000 BTU mv ng
    Jacuzzi 345 whirlpool bath
    TF-100 test kit, HM digital com100 Wanda the Whale

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    Re: Pool level going down

    Quote Originally Posted by banditig View Post
    Any luck finding cause of problem?
    Yes sir. I did the bucket test several times last weekend and it looks like I lose 1/8" in less than 12 hours by evaporation. Same in the pool. That means that the pool is not leaking but that doesn't explain the water in the backyard and the soaked grass. The water is located where the overflow drain is running which doesn't make any sense ...

    Maybe I will dig it up one day ...

    Losing 1 inch a week seems odd during winter in Houston area since my coworkers told me they lose almost no water.

    Thank for your help guys
    G
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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    Re: Pool level going down

    I hate to be a downer, but an inch a week loss in the winter sounds like a small leak. Water in the yard and soaked grass sounds like a leak.
    10,000 gallon in ground diamond brite, Circupool si30+, Hayward C900 cartridge, 1.5hp Flotec single speed pump

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    Re: Pool level going down

    Quote Originally Posted by buzzard302 View Post
    I hate to be a downer, but an inch a week loss in the winter sounds like a small leak. Water in the yard and soaked grass sounds like a leak.
    Agreed. But the bucket also loses an inch a week ...
    Guillaume B.

    12k pool and spa spillover / In-Ground pool / Gunite pool / Swimclear cartridge filter / Hayward SPX3215Z1PE pump / Installed in 2004 / Intellichlor SWG / Hayward heater H400FDN

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