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Thread: Low Suction & Pressure

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    Low Suction & Pressure

    First off thanks in advance for any help with this issue as I am completely new to pool maintenance and ownership. With that said, I am also far from helpless and certainly know my way around the internet and a toolbox. Hopefully I can provide enough information here that someone can point me in the right direction when it comes to getting this problem solved.

    Background Info:
    We recently moved into a home in Phoenix, AZ who's previous owners had no clue when it came to pool maintenance. The automatic water leveler was shut off, the filters were beyond dirty (starting pressure was near 40psi and the filter cartridges were nearly black) and the water was quickly approaching green. I cleaned the filters, lubed all the O-Rings (filter and pump housing), scrubbed & shocked the pool and brought the pH back to normal. The water is now clear and swimmable. I set the aqualink control panel to turn the pump on for 6 hours every night from 10pm to 4am. I keep 4-6 chlorine tablets in a floater at all times.

    General Pool Information:
    1. Pool is approximately 16,500 gallons and free form shaped.[/*:m:13yq2hq6]
    2. Pool has a spa attached to it that is plumbed into the pool itself, both used to be heated. The heater (broken) was bypassed and new plumbing was installed that did not include the heater.[/*:m:13yq2hq6]
    3. There is a water feature and aerator included in the piping. The water feature does not work as far as I can tell and is turned off via valves. The aerator does work but is off.[/*:m:13yq2hq6]


    Pump Model: A.O. Smith Corp SQ1202 2.6hp
    Filter Model: Pentair Clean & Clear Plus CCP520 (cartridge filter)

    (Potential) Problems
    1. The pressure on the filter reads ~10 psi upon starting and stays there or gradually gets to about ~15psi over time. From what I understand, this is too low.[/*:m:13yq2hq6]
    2. The Kreepy Krauly automatic vacuum usually works but the suction seems poor and it doesn't move very fast. After it's been on for a little while it tends to get weaker. About 2 weeks after the filters have been cleaned the vacuum is nearly immobile until I clean them again. No noticeable change in filter pressure.[/*:m:13yq2hq6]
    3. There are a LOT of bubbles coming out of the return jets whenever the pump is turned on after being off for a few hours. After it runs for a while there are still some bubbles coming out of the returns.[/*:m:13yq2hq6]
    4. One return barely works at all (farthest from the pump) and when it does it's mostly bubbles.[/*:m:13yq2hq6]
    5. The skimmers have fairly poor suction, they don't pull debris into the basket much and there's no visible swirling.[/*:m:13yq2hq6]
    6. There is a small leak at the PVC joint where the water comes out of the pump housing and to the filter; This seems to be past the suction side so I am not sure if air is still getting in here.[/*:m:13yq2hq6]


    When I took the pump apart to lube rings and make sure the impeller didn't have anything stuck in it, I noticed there were small cracks or what appear to be slits caused by chafing in the plastic housing that goes around the impeller. Here is a picture:



    I also made a quick video to give a decent visual overview of our setup:

    [youtube:13yq2hq6]L_R83KrAEeY[/youtube:13yq2hq6]


    Sorry for the lengthy post but I wanted to make sure I covered as much information as I could. Please let me know if there's anything I missed!

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Re: Low Suction & Pressure

    The bubbles are your biggest problem. They're caused by a suction side leak.
    Since the impeller has worn slits in the diffuser you probably should replace them.

    10 psi is completely normal for filter pressure.

    Since it appears that the pressure rises quickly there could be something growing in the water.
    Do you have a good test kit?
    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
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    Re: Low Suction & Pressure

    I do not have a good test kit, I don't think; Unless these little strips you get from home depot are considered good

    The pressure doesn't rise too fast, the filters were dirty in appearance but I only saw a 2-3 psi rise over when I last cleaned them. I honestly only cleaned them again because it was what fixed the suction last time and I figured it might help again. It did, but not nearly as drastically.

    What's the best way to go about finding the suction side leak? I've heard of people using smoke to see if it gets pulled in anywhere along the piping?

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    Mod Squad Bama Rambler's Avatar
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    Re: Low Suction & Pressure

    The easiest thing to do is run water over the piping and fittings. When you see the bubbles stop or lessen, you've found your leak. The skimmer creating a vortex is another common way to get air into the system.

    You should do yourself a favor and get a good test kit. You should also stop using the tablets and go to an unstabilized form of chlorine.

    You have an Aqualink. Do you have a swg?
    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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    Re: Low Suction & Pressure

    No SWG. Here's where I'm at right now:

    [youtube:10rituxb]G4pH9oKjqy8[/youtube:10rituxb]

    1. Ran water over all suction side connections to see if bubbles went away at any point -- no go.
    2. Used smoke on a windless day to see if any was getting pulled in by any connections -- no go.
    3. Replaced & lubed o-ring on pump basket lid -- no go.
    4. Sealed all connections with weather/water proof silicone -- no go.

    A little out of ideas at this point short of calling in a repair guy, thoughts? Could bad o-rings in the jandy valves be responsible for this much air? It seems like a lot and I'm fearing an underground leak which seems costly and difficult to locate.

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    Charlie_R's Avatar
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    Re: Low Suction & Pressure

    Old o-rings in the valves could cause a large amount of air in the suction side, that would be a good place to check.

    Have you tried removing the filter carts, and running the pump? This will tell you if the carts have collapsed, if there is a major pressure difference between with and without the carts.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: Low Suction & Pressure

    I have not tried running without the carts, I can certainly give that a shot a little later today. These valves are labeled as "neverlube" valves, are they still serviceable or would I need to replace the whole thing?

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    Charlie_R's Avatar
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    Re: Low Suction & Pressure

    Depends on how old they are, really.

    As you know your way around mechanicals, you know that "neverlube" would be more of a marketing tool than a truth about the internals of the valves. The soft parts may be replaceable. Check with Jandy.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: Low Suction & Pressure

    chasing suction line leaks is hard , yours should be easy since its such a large leak , that a lot of air

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    Re: Low Suction & Pressure

    what about pump shaft seal?

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    Mod Squad Bama Rambler's Avatar
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    Re: Low Suction & Pressure

    Did you run a steady stream if water over the Jandy valves?

    Those valves can be rebuilt. There are two styles of valves that "lubed" ones which have a grease cup on the side and you have to apply lube to once in a while and the "Neverlube" ones like you have. While they're not meant to be lubed regularly, they are easily repaired. And yes, the stem seal can leak a lot of air into 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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    Re: Low Suction & Pressure

    I don't believe it's a pump shaft seal leak. According to my research this generally would result in water pooling under the pump or getting into the motor housing, neither of which is happening.

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    Re: Low Suction & Pressure

    Quote Originally Posted by Bama Rambler
    Did you run a steady stream if water over the Jandy valves?

    Those valves can be rebuilt. There are two styles of valves that "lubed" ones which have a grease cup on the side and you have to apply lube to once in a while and the "Neverlube" ones like you have. While they're not meant to be lubed regularly, they are easily repaired. And yes, the stem seal can leak a lot of air into the system.
    I haven't tried running water over the jandy valves yet, will give this a shot later tonight.

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    Re: Low Suction & Pressure

    probably wont help a lot but i think you are missing a skimmer diverter.
    Walnut Creek, CA. 18k gallon Pebble Sheen + 1.5k gallon IG spa, 1.5hp whisperflo main pump, Pentair clean and clear 420, Intellichlor IC20, Polaris 360 w/booster,Jandy lite 2 natural gas, plus solar with Heliomatic 5000 controller and 3/4 hp booster

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    Charlie_R's Avatar
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    Re: Low Suction & Pressure

    To my limited knowledge, a pump shaft seal will allow water out, especially when running. I would think it highly doubtful it would be allowing air in, just from the design of a centrifugal pump. What you would see on the back side of the impeller is "slippage" pressure, from water escaping the normal flow path. The suction side of the impeller would be the only area you would see negative pressure.
    15'x48" 4500 gallon Intex pool, buried 1.5 ft. Pac-Fab Dynamo 3/4 hp pump. Hayward S180T sand filter, bought used. Taylor K-2006 test kit. Rocket mass heater based wood fired pool heater.

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    Re: Low Suction & Pressure

    Quote Originally Posted by kahmeal
    These valves are labeled as "neverlube" valves, are they still serviceable or would I need to replace the whole thing?
    Jandy neverlubes are completely serviceable. You can get every little part in them. There is one o-ring around the cover held on with all the screws. Then there is one or 2 smaller ones where the handle comes through the cover. However, if you were sucking air at the Jandy valve you should be able to detect it easily with your hose test.
    17x37 IG vinyl, Grecian style, 20k gal, Hayward DE4800, Hayward Super Pump II 1 hp, Rainbow 320 Chlorinator, 6 Vortex 4x10 solar panels, Aquabot Turbo, Dolphin M5, loop-loc mesh cover

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