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Thread: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

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    Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    i have a 40,000 gallon backward L shaped pool.
    has a skimmer in shallow and deep ends & and a drain at bottom of deep end

    just replaced a bad vari-flow valve this year and had no problems except for air pressure building up in sand filter.
    i have worked on the pool for years and never had it build up pressure so quick. and i cant use my timer because i have to release the pressure everytime before i cut the pump off.
    when i removed the old valve the sand filter drained completely. when installing the new valve i just reconnected it to the filter dry. was that okay?

    if the pump cuts off with the air pressure built up and does not get released it will force all the water going into pump to go backwards back towards pool. and when the pump is turned back on water will not flow. i have to take a water hose to fill the pump filter back up with water and turn pump on. then i have to repeat a couple more times to get the water flowing again.
    the sand has not been replace for probably 7 to 9 years
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    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    Welcome to TFP!

    Nice looking pool!

    Someone will be along shortly who will be able to help you!

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    1. What is the maximum psi you see on the guage when the pump is primed and running?

    2. Can you feel water going back into the pool at the returns?
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    Quote Originally Posted by duraleigh
    1. What is the maximum psi you see on the guage when the pump is primed and running?

    2. Can you feel water going back into the pool at the returns?
    1 - max PSI is around 30-35
    2 - havent tried yet, will try this afternoon

    i did replace the oring on the screw on top off the pump filter basket
    i ran it all night and this morning didnt take as long to release the pressure.
    i also noticed that where the metal T comes out the top of the sand filter i am seeing some air bubbles coming out. i tried to tighten but just turns and turns. should i take the top off the sand filter and check it out?
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    i cant use my timer because i have to release the pressure everytime before i cut the pump off.
    I am confused by this. How do you "release" the pressure?

    It is very important to know that water is or isn't flowing back into the pool. Please post that info back.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    Quote Originally Posted by duraleigh
    i cant use my timer because i have to release the pressure everytime before i cut the pump off.
    I am confused by this. How do you "release" the pressure?

    It is very important to know that water is or isn't flowing back into the pool. Please post that info back.
    i release the pressure by opening the pitcock valve on top of sand filter.
    at the top of the sand filter i have a T that goes to that pitcock valve to release pressure and the PSI gauge.
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    It is very important to know that water is or isn't flowing back into the pool. Please post that info back.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    Water is flowing back in the pool.
    it seem the air pressure is building up so great that if the pump it cut off and the pressure does not get released all that pressure is send backwards throught the pump back in to the lines going to pull.

    when the pump is turned back on after that happens it will not pull any water. just turns on and pumps air. there is no water flow.

    what i then do is take a water hose and fill up the skimmer basket by the pump with water and turn it on. i have to repeat that process about 3 or 4 times then its back to normal.

    i have bought a new oring and lube for the pump skimmer.
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    You are losing prime. For the pump to work properly, air cannot get into the system.

    After you have operated normally and then shut the pump down, air is getting into the system.....most likely from a leak on the suction side.

    If the leak was on the pressure side, you would see water leaking at that point when the pump was functioning normally......you don't, do you?

    Assuming you don't see any water leaks, air is getting into your system somewhere between the skimmers/main drain and the pump.

    When you finally have the pump operating normally, do you see any bubbles in the pump strainer basket?
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    Quote Originally Posted by duraleigh
    You are losing prime. For the pump to work properly, air cannot get into the system.

    After you have operated normally and then shut the pump down, air is getting into the system.....most likely from a leak on the suction side.

    If the leak was on the pressure side, you would see water leaking at that point when the pump was functioning normally......you don't, do you?

    Assuming you don't see any water leaks, air is getting into your system somewhere between the skimmers/main drain and the pump.

    When you finally have the pump operating normally, do you see any bubbles in the pump strainer basket?

    i do see a few leaks.
    when the skimmers and drain lines come to the pump, all 3 flow to a manual valve to use just the skimmers for main drian. there is a little plug to the side of that where water is leaking from.

    also where the pump is banded to the pump basket, it is leaking water at a steady drip.

    also, at the bottom of the pump basket there was a hole that i had to put a plug into. in years past there was a bolt there, but it fell out this year and i replaced it with plug. THERE IS NO LEAK THERE, BUT THAT IS SOMETHING THAT CHANGED.


    also at the top of the sand filter there is a pressure gauge. i can see air leaking out around that metal T that connects to pressure gauge. but that is where my pitcock is and where is usually release the pressure.
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    For your system to work properly and not lose prime, all those leaks have to be stopped.

    Once you get those leaks cured, I think your pump will hold prime and you will find turning it on and off very easy.

    What is that moster looking pipe with duct tape on it just above your pump? I would suspect you are leaking air there as well.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    that large pipe was hooked to a dial to control the copper or something like that. it was setup and installed long before i took over the pool.

    how do i know if the sand filter's sand needs to be replaced? i know it was replaced mayber 6 or so years ago.

    thanks for all your help on this matter. it is much appreciated.
    i am gonig to try and fix those leaks this weekend and get back to you....
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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    Re: Sand Filter Building Pressure -Just Replaced Vari-Flow Valve

    well i got it! right before the pump basket there is a valve to select the main drain or skimmers or both. well there was a plug on the front the broke off and a small hole was there. i put my finger over the hole and i could see all the way down to the bottom of the pump basket. when i released my finger air bubbles started to pour in.

    so i sealed the hole and it works like a charm. thanks again for the help
    The following is a cheap test pool to learn from before purchasing a 27ft one.

    1700 gallon AG intex all in one metal frame pool. Filter system is an old Jacuzzi 200lb filter with an old Hayward 1hp pump.

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