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Thread: Low suction at skimmer

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    Low suction at skimmer

    Can someone please help me figure out why my skimmer suction is low?
    I've searched for hours on the forum and can't figure it out.

    Pool stats are in signature but to reiterate with other pertinent info:
    Approx. 30K gal. - 18x36- in ground with vinyl liner- Hayward sand filter- one speed 1/2 horsepower pump.
    One bottom drain- One sidewall skimmer
    Two jets/returns, one in shallow, one in deep on opposite wall of skimmer.

    First, water wasn't moving well. Returns with low pressure & skimmer low suction. Pressure gauge on pump read 25psi. Also small amount of water on filter tank coming from under flange clamp.
    Backwashed & rinsed. Psi to 15 which is my clean normal. Backwash water was not dirty however and should be with lots of pollen.
    Dried water on filter tank. No more noted rest of day. Returns improved with backwash to normal pressure. Water moving well.
    I read in a post that the valve/tank O-ring should hold up to 50psi so I need your opinion on replacing this too.

    Some slight bubbles in filter basket. None at returns. Checked gasket. Some debris on gasket and slightly bent one area. Replaced gasket. Made sure no debris on inner lid, gasket or basket surface.
    Still low skimmer suction.

    Skimmer has two holes open. ( can't say I've ever noticed this before because never had issues with suction before)
    In reading posts one without suction could be for drain. Most reply post say the holes need a diverter which we've never had. May have had a plug that dislodged somehow and I didn't notice but not a diverter.
    We have 2 pipes at pump to open and close skimmer and drain.
    Photos below.

    There is possibility of debris in the line as we have lots of leaves and small things off trees getting into pool.
    We try to be very careful but a small leaves and small debris does get past us when emptying the skimmer basket sometimes.
    If it were debris, would the returns be forceful?

    Waiting for my experts to tell me what to try next.
    Thank you!
    Joan
    Attached Images Attached Images
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Re: Low suction at skimmer

    Joan,

    Does the flow return when you backwash and then get slow after a while?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Texas Splash's Avatar
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    Re: Low suction at skimmer

    Hi Joan! Along with Dave's question, a few things do come to my mind as well when I read your story. One is the debris in the line. It is possible that some leaves or something are partially clogging your suction line from the poolside skimmer to the pump strainer basket. If that's the case, you might try a plumber's snake or a bladder device (i.e. Drain Kink) designed to seal the pipe around the end of a garden hose while pushing pressure forward.

    As you noticed, it's also possible that one of the two skimmer holes is simply plugged and was never plumbed. The main drain may simply be plumbed by its own line to the equipment pad - hence the 3-way valve to adjust which suction source you want.

    Also, I'm not sure about your pump. In the description above you mention a 1/2 HP, but in your sig it says 1 HP. So that may be part of the problem as well. Also, it's a single speed which tells me it's not very efficient, not only in its operation but for your electric bill. In the future, you may want to consider replacing it with a newer 2-speed, perhaps 1.5 - 2 horsepower.

    As you have noticed, a dirty filter will impede pressure as well. Have you ever done a deep cleaning on that filter? If not, you may want to consider doing that next time you have time. See Deep Cleaning a Sand Filter.

    Hope some of this makes sense and helps you. Feel free to post back as much as you need to. We'll be hanging around to help.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Mod Squad jblizzle's Avatar
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    Re: Low suction at skimmer

    Pat, note that the 3-way valve is on the return lines. The 2 red ball valves control whether the suction is from the skimmer or floor.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: Low suction at skimmer

    Thank you Dave and Texas Splash.

    Dave: No the skimmer flow did not return after backwash.

    Pat: It is possible that some debris may be clogging the line from the skimmer to the pump strainer basket.

    My husband said the two pipes behind the pump with red valves on them were one on right for the drain and one on left for the skimmer. I think the 3-way valve you mentioned is the gray valve atop one of the pipes to the left behind the sand filter. That is for the lines that go to the old shark that the previous owners had. That is closed off and not used. I should have mentioned that. The extra hole in the skimmer may or may not be plumbed but the red valve behind the pump cuts of the drain at the deep end for sure.

    My mistake. My pump is a 1HP. Not a 1/2HP. This is what the "pool guy" suggested.

    As for a dirty filter, I had backwashed this past weekend and so each weekend. And yes, I did a deep cleaning of the filter last season and even posted pics her on the site .

    Something (s) aren't working correctly as the backwash water wasn't even dirty. It should have been at least yellow with all of the pollen we're having plus my water has a great deal in it and is cloudy from it.

    My husband vacuumed Saturday and didn't notice reduced suction at the skimmer so whatever happened has built up or happened since then.

    Continued analysis please. If you can do so with my descriptions.

    Thank you,
    Joan
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Texas Splash's Avatar
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    Re: Low suction at skimmer

    Joan, my correction - you and Jason clarified the 3-way valve is on the pressure side. I missed that one. Is it possible about the skimmer line being clogged? ... sure, but before you get too far into that, I think based on your comment about cloudy water, that we should ask the most important question ..... can you post a full set of test results? "If" you have algae beginning to bloom, that will most definitely trigger flow problems. It would be good to know what your chemical readings are before you get too far into the mechanical side of things. No amount of filtration can keep-up with algae.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Low suction at skimmer

    I can get you some numbers in the morning Pat but I don't believe algae is my problem at all.
    This isn't algae cloudy it's POLLEN cloudy that I experience every year.
    Another reason I don't think it's algae is because I have a "special needs" pool.
    AKA - one with iron in the water ( source unknown) and it gets 16 oz of polyquat in it a week since the temp has been 60 and above.
    So for about 5-6 weeks now I've put polyquat 60 in because I really don't want an algae bloom and have to shock and end up with a stained liner all over again.

    I haven't even begun to balance yet. I've just been making sure the polyquat is in since the weather has started to warm a little.
    I had intended to do that this weekend.
    As before, I can get some numbers in the morning. I need to get started on it anyway and was what I was headed toward today.

    Thank you so much!!
    Joan
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Re: Low suction at skimmer

    Polyquat is not a good algae killer....chlorine is.
    First, water wasn't moving well. Returns with low pressure & skimmer low suction. Pressure gauge on pump read 25psi. Also small amount of water on filter tank coming from under flange clamp.
    Backwashed & rinsed. Psi to 15 which is my clean normal.
    When I asked if your flow returned, I was talking about the flow from the jets in thje pool, not the skimmer. Your quote above seems to say that but I am just clarifying.

    So, regardless of color or anything else, If your psi is 25, you backwash it and it goes to 15 but then goes back up to 25 after (4, 24, 48 hours??), then your filter is doing exactly as it is supposed to do, gathering debris from your pool and catching it......that's why the psi goes up.....there is more resistance in the now dirty filter.

    If that is the case, it is classic of algae in the pool (invisible) and a SLAM is the correct procedure to clear the pool.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Low suction at skimmer

    Rain this morning and clouds so no numbers yet.
    These will be "opening" numbers so to speak although we don't cover and close our pool.
    We keep debris out during the winter but don't keep it balanced. I start balancing when the weather starts to warm up. It's that time now!

    I agree Dave. The polyquat isn't meant to kill aglae. I had used it as a preventative until I had time to see where my numbers are get the water balanced.
    I will see where I am with those and say my prayers that I don't end up in a SLAM. It will be what it will be.

    As for flow: Flow from the jets into the pool came back strong after backwash. psi went down from 25 to 15 and has not gone back up after 24 hours.
    Jets remain strong.
    Both the drain and skimmer were fully open yesterday. I closed the drain 1/2 and the skimmer flow was better this morning.
    How strong is it supposed to be? Is there a way to test the skimmer suction for strength?

    Gonna do numbers and go get some CYA and whatever else I may need. I hope my mixer is working right when I start adding things.

    Thank you guys,
    Joan
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Mod Squad jblizzle's Avatar
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    Re: Low suction at skimmer

    You should really keep it balanced all winter to avoid problems.

    I have never understood why people use the raining excuse to not test their water ... run out, get a sample, and go back in the house to test. Everything will be fine assuming your pump is running. The CYA will be off due to the lack of bright sunlight though.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Re: Low suction at skimmer

    Thank you for your suggestion and comments Jason.

    I realize many do not agree with not balancing water in open pools over the winter. I've read much discussion on the forum regarding whether algae will or will not grow in colder water.
    In the 14 years we've had this pool, I've had an algae bloom only two separate springs when the weather warmed early before I got the water balanced/chlorinated.
    Other than the chlorine the other numbers don't get too far off.

    Not being able to get a CYA reading was exactly why I didn't get samples in the rain or with cloudiness.
    As it turned out we had sun this afternoon and I got numbers. It didn't help with getting a good CYA reading after all however. Thought I had it down last year but could still see that dot all the way to 0!
    I even used the test re-agent that I got last year instead of my pool water to be sure my CYA re-agent was still good. It seemed fine.
    My CYA at end of last season was 25. I have backwashed several times throughout the winter months with rain so IS it feasible that it is truly 0?

    Cl- 0 (didn't even test. I know there isn't any in there)
    CC-0
    Ph- 7.2
    TA- 30
    CH- 90
    CYA-0

    added 2qts & 3c baking soda TA- 50 & Ph 7.5
    That was all I had. I've gotten more and gone back to pool calculator.
    Will add more for TA goal of 70
    Will add 10% Chlorine for goal of 3ppm
    Adding stabilizer to skimmer for goal of 30 unless someone tells me otherwise.

    I will also add Metal Magic sequestrant as I have iron.

    Thank you
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Texas Splash's Avatar
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    Re: Low suction at skimmer

    Joan, since your FC AND CYA are at zero, please do one thing before you add the stabilizer. Add bleach for a target of about 10 ppm. Then test it in about 10-15 min. If you still have FC in the water, then yes, add stabilizer for a target of 30 ppm, and increase FC to 12 for your SLAM. If your FC disappears almost immediately within that 10-15 minutes, let us know. Otherwise, press-on with the SLAM and make sure to follow the instructions carefully. It will serve you well. Have a nice evening.

    - - - Updated - - -

    Oh, and double-check the sequestrant instructions. You might want to hold-off on adding until after the SLAM when you can let the FC drop a little. Double-check.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Mod Squad jblizzle's Avatar
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    Re: Low suction at skimmer

    Well one possibility with 0 cya is that it was converted to ammonia over the winter when the chlorine drop to zero. The solution is the same however add more chlorine. If you see your FC drop quickly and your CC rides and then that could be what happened.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    Re: Low suction at skimmer

    You guys are great! Thank you!
    I'm probably doing the SLAM. Color me NOT HAPPY!
    Found some hiding green stuff around jets and skimmer inlet late yesterday when brushing.

    Yes, hold off on sequestrant. Not wasting it. I'm going to have a green pool once that chlorine goes in !
    This is the demon I dread and have to face it. I'll just have to deal with stains after the SLAM.

    I can't start a full on until late today or tomorrow. This has been part of the problem past few weeks. Kept saying I have to test and get Chlorine in but been busy.

    I'll spare you all the pity party and simply say thank you. Seems as though if I need further help I may need to move out of Pumping Station?

    Oh! Filter did build back up a bit to 20psi so backwashed a little this morn. Skimmer suctions looks good with drain cut to half.

    Thank you so much!
    Joan
    JoanC--Rome, GA
    18.5 x 41 Grecian IG Vinyl--34,000 Gallons
    Hayward S244T -Sand Filter - design flow rate 62GPM, Turnover 29,760 G/per 8hr
    1 HP-single speed pump motor. TF-100 Test Kit, SpeedStir
    Presume pool built with house 1989. Owner since 2002.

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    Texas Splash's Avatar
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    Re: Low suction at skimmer

    You're welcome Joan. We understand. Pools aren't all we do either. When you are able to settle down for a bit and do that SLAM, review our notes and let us know if you have any questions. We'll be around to help. Have a nice weekend.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Low suction at skimmer

    Joan, if you are concerned that the SLAM is going to precipitate iron (turn your pool clear green) PM me and I may be able to help.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Low suction at skimmer

    Make sure your skimmer has a working Weir door (the flat piece in the skimmer throat that floats up and down with the water level). If the door is missing, your skimmer will not appear to have flow even though it is taking in water. I just went through this on one of my two skimmers. The door was missing and after I replaced it the gain in the apparent (visible) flow was amazing.
    38000 Gal, IG, Plaster, 20' x 40' x 10', Attached Raised Spa, Intelliflo VS 3 HP (011018), Pentair Quad DE 60 Filter, Raypak (Rheem) 400,000 BTU (407a low Nox), Easy Touch 8 upgrade, Screenlogic 2 with wireless, IS-4 Spa Side Remote, Stenner 45MPHP10 w/15 gal tank, Intellibrite 5g (3), Dolphin Triton Plus robot with PRO remote, Water Tech Catfish handheld vacuum for spa, TF100 with SpeedStir.

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