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Thread: High filter pressure and pump won't prime

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    sammm's Avatar
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    High filter pressure and pump won't prime

    I heard my pool gurgling this morning when the filter was supposed to be running. A lot of air was being injected in the water thru the jets. I checked the equipment and the pump wasn't priming. Water was flowing, but it never filled the basket and primed.

    I was just out there looking things over again. Checked the impeller and o-rings. No problems there. I cranked it up and happened to notice the top of the filter (stainless steel) actually bow up and the pressure jumped up to 50-60psi in a few seconds (normally around 15psi). I took the filter top off and removed the DE panel assembly. Turned pump on and the basket filled in a few seconds. The filter is staying under high pressure even with no pump running.

    I guess this all means I have something clogging my pressure side. Right? What now?
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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    Is there a way to rig it up so that you can suck through a jet and blow through the skimmer with the pump? My brother had his filter connected backwards before and it does work, although incorrectly.

    Maybe you could blow the obstruction out. Either that or you may have a broken pipe which is now full of dirt. Hopefully not though.
    steve

    Above Ground / 18' Round / Vinyl Liner / Sand Filter / 100K Gas Heater / Salt Added / No Nature2

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    mas985's Avatar
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    With that much pressure it sounds more like dead head. Returns pipes generally do not have any debris blockage since they are after the filter so that makes me think that you may have some valves in the wrong position or even off.

    If the valves are ok, then the only other thing it could be is the filter itself. Grids are completely blocked so you may need to take it apart.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    The filter is staying under high pressure even with no pump running.
    If that's the case, and you have no check valve between the pump and filter, I think you have a broken guage.

    Unless I don't understand DE filters, the pressure should be relieved backwards or forwards with the pump off regardless of any blockage.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    sammm's Avatar
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    sevver - I hope it's not a broken pipe buried somewhere.

    mas985 - I just took the filter apart and cleaned all the grids a few weeks ago. When I opened the filter earlier today it still looks very clean to me.

    duraleigh - What I meant was the filter pressure stays high (around 20psi) even after the pump is turned off.
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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    duraleigh - What I meant was the filter pressure stays high (around 20psi) even after the pump is turned off.
    Still sounds like a bad guage...pressure should be 0.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Is the gauge stuck on 20psi? It could be broke, take the gauge off, if it does not go back to 0, then it definitely is.
    steve

    Above Ground / 18' Round / Vinyl Liner / Sand Filter / 100K Gas Heater / Salt Added / No Nature2

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    The gauge is at 20psi, but it's valid. Even when the pump is off, if I open the air-bleeder valve on top of the filter I get a hard steady stream of water. The gauge will eventually go to zero. As soon as I turn on the pump again, the pressure jumps up to 50-60psi.
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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    To get that effect the return line has to be completely air tight blocked and there needs to be a check valve on the suction side of the filter. A check valve isn't unusual, but about the only way to get an air tight blockage that can hold 20 psi is to turn off all the valves on the return side of the filter.

    Make sure all your return valves are open, or if you aren't sure what is what turn one of them and see if anything changes.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    That is such a puzzling issue.... If it drops from 50-60 to twenty, why does it stop at twenty?

    Another side issue, to my knowledge, pool pumps are generally incapable of much more than 35 or so psi...I know mine stops around 36.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Dave has a good point. A high head 2 HP pump will dead head somewhere slightly north of 90 feet which is just shy of 40 PSI so it is unlikely that the PSI will climb above that.

    You may have several things going on one of which is that the guage may not be measuring pressure correctly. Because you have a blockage in the return side, after you turn off the pump, it may take some time to fully release the pressure backwards through the pump.

    Second, is there a way you can bypass the filter with the backwash valve to see if the pressure drops?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Thanks for all the replies! I know the pressure was very high because I could literally see the top of the filter (stainless steel) expand and bow up.

    I don't know what it was, but it's working normally again today. I did take everything apart yesterday (filter, checked impeller) and checked my valves. I thing I noticed is I'm having to 'bleed' air from my filter almost daily. Could that be a hint to what the problem is/was? Can air get trapped in a return line?
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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    It is more likely that you are sucking in air from the suction side. Do see any air in the pump basket?

    Also, most filters will expand even with pressure as low as 10 PSI so that doesn't mean that you have high pressure only some pressure.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  14. Back To Top    #14
    sammm's Avatar
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    Quote Originally Posted by mas985
    any air in the pump basket?
    Yes, there is an air bubble in there. I lubed the cover o-ring, but same results.
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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    Then it could just be a leaky valve some where or perhaps somewhere else. Sometimes you can find the problem by putting water over the valves and piping as see if the air goes away.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    I have a leak on the garden hose bib on my return. As such all the water drains from the filter and the return plumbing daily. When I start up I get tons of air out of the returns and have to bleed the filter. It's no big deal though so I doubt that's your issue.

  17. Back To Top    #17
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    I solved the high-pressure issue, but I'm still having problems getting the pump to prime. I replaced the basket cover o-ring, but still no luck. Water is pumping in and it will catch prime for a bit, then the water will drop suddenly and start trying to prime all over again. Any ideas on how to track down my problem? Thanks in advance!
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

  18. Back To Top    #18

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    As mas described, you can put a stream of water (not jet pressure, just the garden hose without a nozzle) over your fittings, valves, plumbing joints to see if the bubbles stop. Instead of the garden hose, I use a wet rag and wrap it around the same locations...all on the suction side of the pump. It should stop any air leaks and it will help you isolate the location of the leak.

    what was the cause if the high pressure?
    Sean Assam - Sean@teamhorner.com
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  19. Back To Top    #19
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    Quote Originally Posted by Poolsean
    what was the cause if the high pressure?
    That's still a mystery, but it's gone for now at least. I'll try the wet rag trick and see what I can find. Thanks Sean.
    WetEdge Satin Matrix, 16K gallon, Pentair NSP-60 DE filter, Pac Fab Challenger, 2HP pump, BBB, Polaris 360

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