Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 14 of 14

Thread: Pressure starts dropping and raising, dropping and raising

  1. Back To Top    #1

    Pressure starts dropping and raising, dropping and raising

    Hello all, I have a Whisperflo with a 2Horse Power motor, all is good until about 2 hours of the pump running, then the pressure drops almost exactly 10psi and then rises again, say the pressure reaches 25psi, after a few hours it drops to 15, then swings up to 25, then drops again. They tell me to check for leaks or possible air getting into the flow.
    We took the whole filter apart, brushed and washed everything, looks almost new, started with fresh earth.

    Another thing, we can make it swing up and down on the pressure as soon as we turn on the booster pump for the polaris sweep. We also replaced all the hoses for the booster pump.

    Anyone has seen this situation? What to do beyond checking for water leaks or air intake?

    Thanks

  2. Back To Top    #2

    In the Industry
    Nasty90's Avatar
    Join Date
    Apr 2008
    Posts
    48

    Re: Pressure starts dropping and raising, dropping and raising

    Hello, welcome to the site!

    Can post a bio about your pool and if the pump location is above or below pool grade?
    35000 in ground vinyl liner with cartridge filter
    Birmingham,AL

  3. Back To Top    #3

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,409

    Re: Pressure starts dropping and raising, dropping and raising

    Another thing, we can make it swing up and down on the pressure as soon as we turn on the booster pump for the polaris sweep. We also replaced all the hoses for the booster pump.
    Clarify that, please. What happens to the psi the when you turn on the booster pump? What happens when you turn it off? Does it stay steady in you leave the booster on?

    Are you saying this is related to your first problem with fluctuating pressure or that you think it is a separate problem?
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  4. Back To Top    #4

    Re: Pressure starts dropping and raising, dropping and raising

    Wow, thanks for the quick replies.
    Pool is kidney shaped, inground, we guesstimate about 20thousand gallons, pumps and filter at at same level as the top of the pool.

    When we turn on the booster pump, the pressure drops and jumps up again, and again. We can make the pressure behave like that as soon as we turn on the booster pump, otherwise it takes about a couple of hours to do it on its own.
    Once the pressure starts jumping like that, does not matter if we turn off the booster pump, it stays swinging up and down.

  5. Back To Top    #5

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,409

    Re: Pressure starts dropping and raising, dropping and raising

    When we turn on the booster pump, the pressure drops and jumps up again, and again
    At what time interval? Every three seconds? Every Three minutes?
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6

    Re: Pressure starts dropping and raising, dropping and raising

    Once it starts to swing, it's a constant swing, maybe three seconds at 15psi, jumps to 25psi for three seconds, drops again to 15psi, and so on.

  7. Back To Top    #7

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,409

    Re: Pressure starts dropping and raising, dropping and raising

    I don't think I've seen or heard of that issue before.

    In a typical pool, 15psi is pretty close to normal so that would seem to indicate that something on the pressure side of your system is restricting the flow in a rhythmic manner.

    I am assuming you have attached no fountains, etc. to the returns that could cause that rhythmic restriction so the only other place I can think of that might have some type of moving part (that isn't supposed to move) is somewhere inside your filter.

    I have little knowledge of DE filters so I am not much help beyond that.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  8. Back To Top    #8

    Join Date
    Mar 2007
    Location
    Coastalish 'down easter'
    Posts
    4,160

    Re: Pressure starts dropping and raising, dropping and raising

    Ok - I'm just 'thinking out loud here' (in hopes it will spark some idea in someone else)
    What we've got is a 'surging' high pressure issue - the psi goes up 10 on a regular basis, and can be made to do so by running the booster pump. The fact that it doesn't go to "0" indicates that it's not a suction side air leak. (... unless the pressure gauge is broken and 15 PSI is as low as it goes... ) Knowing the flow from the returns at both the high and low point might tell us something! (actually, as I think of this scenario, it makes much more sense) Another question is whether the pump is fully primed during the pressure change? (skimmer weir) With out a suction side problem (which could be exacerbated by a clog or a stuck weir) there would HAVE to be a cyclical pressure problem (return 'eyeball' 'rolling' ), but why would running the booster pump cause this ...

    In this process of thinking myself through this, I DO believe that it's a suction problem! and you need to look at the skimmer weir and/ or a suction problem - increased air in the pump housing (coupled with a broken pressure gauge) is all I can think of that would make the system act like this.



    Please see if anything I've brought up in this post applies to your situation -- welcome to TFP!!
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  9. Back To Top    #9
    launboy's Avatar
    Join Date
    Jun 2008
    Location
    S.E. Wisconsin
    Posts
    582

    Re: Pressure starts dropping and raising, dropping and raising

    I was basically going to say what Waste said. At the Water Warehouse we buy chlorine at, they have 7 or 8 pools setup outside and one of them had that surging issue. You could hear it very clearly, and when I went over and looked in the skimmer(the top was off) the weir was all the way down. It still couldn't let enough water in(low water level in pool) and when the pump would suck a lot of air it would suck less water. The skimmer then could fill with water which would fill the pump and cause it to pull more again. This caused it to rhythmically surge about every 2-3 seconds.

    If you have air in the pump skimmer, this might be the problem. Having something looses in the filter that is flapping also makes sense. Think about it, when it opens more water flows and somehow closes it, then less water so it opens again. When the booster pump is turned on(assuming it's inlet is after the filter) it creates less back pressure on the return plumbing. This causes more water to flow( ) or at least create the same circumstances as if more water were flowing, thus causing the flapper thing to close again and repeat.

    I was kind of thinking out loud when typing that stuff... I don't know much about D.E. filters at all, so I don't even know if a "flapper thingy" in one is even possible.

    HTH,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

  10. Back To Top    #10

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,409

    Re: Pressure starts dropping and raising, dropping and raising

    The skimmer sucking air would make sense if the psi was from 0 surging to 15. I'm not sure that wouldn't be more intermittent than rhythmic as well.

    The 15-25 psi fluctuation seems to indicate it's on the pressure side of the system but I can't imagine what the heck the restriction is, tho.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  11. Back To Top    #11
    launboy's Avatar
    Join Date
    Jun 2008
    Location
    S.E. Wisconsin
    Posts
    582

    Re: Pressure starts dropping and raising, dropping and raising

    The guage might be inaccurate and even though it says 15, it might mean 0. I noticed on my new guage when I replaced it this spring that it says to remove it from the filter and store it where it won't freeze. I don't think many people do this.

    ElGuito, when you turn the pump off, does the guage go to zero?

    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

  12. Back To Top    #12

    Re: Pressure starts dropping and raising, dropping and raising

    Discovery!
    Where the massive 2 inch pipes attach to the side of the filter, there is a top hookup labeled "OUTLET" and one below "INLET", the large PVC "nut" which attaches "OUTLET" to the filter was very loose, i tightened it as far as it would go by hand and for good measure a few gentle taps with rubber mallet.
    Starting with a pristine clean filter grids, manifold, etc. we turned on the main pump and after a few hours no swing in pressure! YAY!
    We even turned on the booster sweep pump, no problem, the Polaris sweeper came off the hose so the hose is swoshing around, still no drop and rise in pressure.
    It's been weeks of replacing about everything, so we'll keep an eye on it, but tightening the OUTLET (and for good measure the INLET) large PVC nuts seems to fix it. PHEW!

  13. Back To Top    #13

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    28,409

    Re: Pressure starts dropping and raising, dropping and raising

    The "fix" is every bit as puzzling to me as the problem. That said, I'm glad it's working for you.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  14. Back To Top    #14

    Re: Pressure starts dropping and raising, dropping and raising

    Yeah, we were close to desperate, but just for good measure we cleaned all elements in the filter, again, started it clean and added, very, very slowly fresh diatomic (spell?) earth, and from about 12psi has gone to 28psi, but we've been brushing and sweeping, keep in mind that we haven't had a steady flow for months!

    Not to advertise or anything, but the Whisperflo motors are close to silent, I have my window open and cannot hear it, most important, just two days ago I could hear it whinning up, down, up, down.

    Thanks all!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •