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Thread: Help With Back Pressure and Debris in Pump Strainer Basket

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    Help With Back Pressure and Debris in Pump Strainer Basket

    Hi All,

    I was doing doing my pool routine tonight, and I noticed while the pump was running there was a large ball of debris in the pump's strainer basket. The debris was pressed up against the side of the basket and blocking the pump's outlet, but as soon as I turned the pump off, the debris got sucked back into the suction line. The pump lid isn't crystal clear anymore, so I can't be 100% sure, but it looks like the debris is just normal leaves and "strings" from the palms.

    I have a couple of questions:

    1. Since I haven't had a lot of debris in the pool so far (I've only owned it for 9 months, so I haven't had the pleasure of a fall season yet), it is entirely possible this back pressure has always existed and I just never noticed it before. Is it normal to have back pressure at the pump? If it is not normal, is it harmful, what causes it? I bought new cartridges for the filter in about April, and the pool was barely used over the summer, so I can't imagine the cartridges are clogged.

    2. Regardless of whether the back pressure is normal, how do I at least temporarily stop it so I can clear out the debris?

    Thanks in advance for your assistance!

    - Eric
    IG 22,500 gallon plaster pool (35' x 16' x 7') with spill-over spa (6'), circa 2004
    2HP WhisperFlo pump w/Pentair Clean & Clear Plus Cartridge Filter
    3/4HP WhisperFlo for two sheer arc waterfalls
    Suction-side Poolvernuegen
    Eric in Brentwood, California

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    Mod Squad kimkats's Avatar
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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    If I am reading this right what you are saying is that when your pump is running you can see stuff in the basket that sits right in front of you pump. When the pump is turned off the stuff goes back into the pipe it came from (the pipe that comes from the pool skimmer).

    When I see stuff in my pump basket area that did not come out with the basket I just open the valve just before it and let the water overfill the basket holder and flush it out.

    I do not have the problem of the stuff getting sucked back into the pipe BUT I have an AGP so...........

    I hope this helps.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    It's entirely possible it was always there. Debris in your pump basket also shows that is it getting past your skimmer(s) basket as well. You need to clean those more often and check to see if they are in working order and properly seated.

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    I try to clean out my skimmer baskets when the pump isn't running, but once in a while I've cleaned them while the pump is running. As a result, a few leaves made their way to the pump basket. I remove them quickly after I notice them, but they have never gone back to the pool (at least that I know of). I have noticed a time or two that a skimmer basket will float. I guess that could be a cause too. Seen that I could put a weight in them to keep them from floating. But, again, I've only seen that twice in the last three swimming seasons I've been here.
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    There is no back pressure in a circulatory system unless you are sucking in air.

    If you suck in air (through a suction side leak), the air will pressurize in the filter and when the pump is turned off, that pressure from the air accumulated in the top of the filter pushes water backwards.

    The solution is to find and fix that suction side leak. There is an article in Pool School that may help.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    If you can't fix the suction side leak right now then a short term solution might be to bleed the air out of your filter before turning off the pump (you will likely find a bleed valve at the pressure guage).

    Alternatively you could close all the valves on the suction side of the pump and then immediately turn off the pump (and I mean immediately...pumps don't like being run dry).
    Cheers, Peter
    20,000 gal, 52'x17' kidney shaped IG, Pebble Tec, IntelliPro P6E6VS4H-209L pump. Intellichlor IC40 SWG.
    300 sf Sta-Rite System 3 cartridge filter. Poolvergnuegen 4-wheel suction pool cleaner. TF-100 test kit.

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    I do know, if your have loose fittings at the filter and the pump is shut off, the water will gurgle back down that line. I believe the back pressure is caused by the water in the filter being higher then the pump. Trust me, I know, happened to me and I had to freaking prime the pump all over again every time the timer shut it off. Once that fitting was tightened, I could turn pump off and the water level wouldn't change in the basket area.

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    I do know, if your have loose fittings at the filter and the pump is shut off, the water will gurgle back down that line. I believe the back pressure is caused by the water in the filter being higher then the pump.
    That can certainly be true but OP describes the "backpressure" as a rather sudden event, which is most always from air in the filter decompressing. A leak on the pressure side of the system with the pump off would more likely be a slow event.

    Additionally, a loose fitting after the pump usually results in a water leak (pump on) which is usually pretty easy to notice.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    This doesn't solve your issues, but you also might want to use skimmer socks to reduce the gunk making its way to your pump basket. They work a treat.

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    Thanks to all for your input and replies. In regards to debris being in the basket in the first place, it is from my suction-side cleaner (Poolvernuegen).

    I was thinking the back pressure could be created by a suction-side air leak, like Duraleigh describes, but there is no air visible in the pump basket after it primes. Would I always expect to see air bubbles in there if there was a leak?

    I do get gurgling, and the water lowers, but only if I take the lid to the pump off. If I'm just turning the pump off, then the water level stays the same and there is no gurgling, just the effect of the back pressure that I described in my original post.

    My pump and filter are above the pool level if that matters in any of this.

    Thanks again for any insight.

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    Re: Help With Back Pressure and Debris in Pump Strainer Basket

    Have you checked when you turn the pump on, if there is any quick lil leak that stops immediately. After the pump is where I would look.

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