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Thread: Another skimmer suction question

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    ship of fools's Avatar
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    Another skimmer suction question

    I have been watching the other thread because i believe i am in the exact same boat.

    Just one quick question - if i shut the main drain off i should still be able to run the pump / pull enough water through the skimmer to keep it running?

    I lose prime almost immediately ...... so i assume i have a clog somewhere in my skimmer line?? .... i can vacuum when both are open but it doesn't vacuum like it should.
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Re: Another skimmer suction question

    so i assume i have a clog somewhere in my skimmer line??
    My first thought is that you are sucking in air at the skimmer.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Another skimmer suction question

    Quote Originally Posted by duraleigh
    so i assume i have a clog somewhere in my skimmer line??
    My first thought is that you are sucking in air at the skimmer.

    can you elaborate on that idea??

    water level is fine .... no bubbles in pump basket when it is running with main and skimmer open
    21,000 gallon inground
    Haywood Sand Filter
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    Re: Another skimmer suction question

    What does the psi gauge do when it drops prime? Have you walked to the skimmer and looked down into it when it drops prime? (pump running)

    If you are sure there is no air being sucked in through the skimmer, then the blockage makes sense. Have you tried a garden hose and pushing water back out through the skimmer line?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    ship of fools's Avatar
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    Re: Another skimmer suction question

    Quote Originally Posted by duraleigh
    What does the psi gauge do when it drops prime? Have you walked to the skimmer and looked down into it when it drops prime? (pump running)

    If you are sure there is no air being sucked in through the skimmer, then the blockage makes sense. Have you tried a garden hose and pushing water back out through the skimmer line?

    I haven't checked the gauge or looked into the skimmer .... are you saying to see if the water "disappears" out of the skimmer / it is being sucked in faster than it can be replaced?? if so i don't believe that is the case ...... my water level is actually a bit high after a bunch of rain lately.

    If not how would air get sucked in through the skimmer?
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Mod Squad Bama Rambler's Avatar
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    Re: Another skimmer suction question

    It's not necessarily getting sucked dry it could just be creating a vortex and sucking air into the plumbing.

    Ideally you should be able to pull from the skimmer alone and not create any problems.

    The fact that you're losing prime means that you're getting air in the suction side somehow. It could be that the skimmer line is partially clogged and when you turn off the MD it increases the suction head enough to make places that normally don't leak, open up and allow air in. Or it could be that the skimmer is sucking in air when it's selected exclusively, either because the weir isn't working correctly or it's missing, or the basket is missing.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    ship of fools's Avatar
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    Re: Another skimmer suction question

    Quote Originally Posted by Bama Rambler
    It's not necessarily getting sucked dry it could just be creating a vortex and sucking air into the plumbing.

    Ideally you should be able to pull from the skimmer alone and not create any problems.

    The fact that you're losing prime means that you're getting air in the suction side somehow. It could be that the skimmer line is partially clogged and when you turn off the MD it increases the suction head enough to make places that normally don't leak, open up and allow air in. Or it could be that the skimmer is sucking in air when it's selected exclusively, either because the weir isn't working correctly or it's missing, or the basket is missing.
    I just checked the things you mentioned.

    The pressure gauge normally reads 18 or 19 psi while running but only drops to 10 or so when i turn the pump off so i am figuring the gauge is working but reading incorrectly since it starts at 10 instead of 0. I have been backwashing when it gets to 22 or 23 and have water to lose anyway since it has been raining a lot.

    When i shut the MD the pressure drops dramatically. When i shut the MD the water is rushing into the skimmer.

    I am now off to find out what a weir is so i can find out if mine is working or missing entirely! only weir i know is Bobby Weir ... the guitarist from the Dead

    UPDATE - The weir appears to be operating properly ... with the pump running it is being pulled back towards the skimmer a couple of inches ... if i push it back towards the pool a little flow increases dramatically.

    If my pool is an inch high on water does that matter?

    When i vacuum i have been running the tube through the skimmer opening and connecting it ... which would hold the weir down thus defeating its' purpose?? .... which doesn't explain my issue because i can't run on just the skimmer even when i am not vacuuming.
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Mod Squad Bama Rambler's Avatar
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    Re: Another skimmer suction question

    You can't trust the gauge. Get a new one and start from there. If it's starting at 10 psi you can't be sure it's linear or at all accurate.

    When you shut the MD does the skimmer suck in air?

    It's actually better that the level's high it helps keep the skimmer from sucking in air.

    What size is your pump?
    What size is your filter?
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    ship of fools's Avatar
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    Re: Another skimmer suction question

    Quote Originally Posted by Bama Rambler
    You can't trust the gauge. Get a new one and start from there. If it's starting at 10 psi you can't be sure it's linear or at all accurate.

    When you shut the MD does the skimmer suck in air?

    It's actually better that the level's high it helps keep the skimmer from sucking in air.

    What size is your pump?
    What size is your filter?
    New gauge - pressure reads 6 psi - drops to 4 or so with just main drain and to 0 with just skimmer ..... with just the skimmer it won't pump water at all - it tries to but loses its prime - looking at the skimmer itself the water flow appears to increase

    pump is 1 hp
    filter is a hayward st244 sand filter - i was having trouble last year so i replaced the sand

    i seem to remember it being better two years ago which was my first year in this house
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Re: Another skimmer suction question

    I found a broken o-ring that caused just enough air to get in causing a loss of prime. check all your o-rings.
    Intex 18 x 52 Ultra Frame Pool Set
    Intex Model: 54955
    Pool Size: 18 ft x 52 in
    Water Capacity (90%) - 6,981 gal.
    sand filter 2100 gph

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    Mod Squad Bama Rambler's Avatar
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    Re: Another skimmer suction question

    Can you post a pic of the equipment pad?

    It sounds like you have an air leak somewhere in the skimmer line. Since adding the MD reduces the suction head, it stops or greatly reduces the air entering the system.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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