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Thread: Is 6 PSI too low?

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    Is 6 PSI too low?

    I just bought new filter cartridges for my pool and installed them. The old filters had been filthy and the PSI was running at 25 before I opened up the filter to replace the cartridges. After I put everything back together, the PSI is now running at 6 PSI and has been that way for the past hour.

    Is this too low? I did have trouble getting the top closure plate to fit flush against the new filters. The notches just wouldn't go in all the way but as the manual said it just had to be "secure" I didn't force them in any further.
    ~20,000 gallon IG Plaster Pool.
    Hayward Northstar 2HP pump.
    Hayward Swim clear C4025 Cartridge Filter.

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
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    Re: Is 6 PSI too low?

    Lower is better, but I'm afraid you have water bypassing your cartridge. How big is your pump?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    mas985's Avatar
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    Re: Is 6 PSI too low?

    On a C4025, the filters themselves should add very little pressure. I have run mine with and without the filters and there is very little change in the pressure. Cartridge filters, especially that line, are usually designed such that the media does not add any head loss. All the loss comes from the fittings and channels inside the filter. The old filters may have calcified some over the years which might explain the higher pressure but like John, I would like to know what size pump you have and if it is a two/multi speed.

    Also, there could be a clog in the pump impeller which would also reduce the pressure.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Is 6 PSI too low?

    I have a Hayward pump but the model # and serial # are no longer readable.

    There's a label on the other side that says the motor is 2 HP.

    I've also got air bubbles coming out of the return line now.
    ~20,000 gallon IG Plaster Pool.
    Hayward Northstar 2HP pump.
    Hayward Swim clear C4025 Cartridge Filter.

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    Re: Is 6 PSI too low?

    It sounds like you might have some water bypassing because the closure plate isn't completely seated. This is pretty common with new cartridges & trying to get the closure plate in for the first time. Make sure all surfaces are wet & you can use a TINY amount of dish soap to help lubricate as they slide together. Wet your finger with soap and run it around the two surfaces. Don't be afraid to bang it pretty good to get it to slide into the cartridge. You won't break it unless you're using a hard tool of some sort.
    APSP CST Certified
    17k inground concrete; 1.5hp 2 speed Tristar pump, 300sq.ft. Cartridge filter, AquaLogic PS-4 w/ Tcell-15, Navigator suction cleaner.

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    Re: Is 6 PSI too low?

    Ok, I did a little banging and got the closure plate flush with all the filters. Still having the same problem. PSI is still hovering at 6 PSI and there are air bubbles in the return line.
    ~20,000 gallon IG Plaster Pool.
    Hayward Northstar 2HP pump.
    Hayward Swim clear C4025 Cartridge Filter.

  7. Back To Top    #7
    Mod Squad JohnT's Avatar
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    Re: Is 6 PSI too low?

    Air in the return and low PSI says you have a leak or restriction before the pump. Are their bubbles in the pump strainer basket? Check that your skimmer is staying full of water, and lube and tighten the pump strainer basket lid.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Is 6 PSI too low?

    There is a little pocket of air right in the dome of the pump strainer lid when I turn the pump off. Is that indicative of a leak? Skimmer is full of water and I lubed the pump strainer lid. My conditions are still the same.
    ~20,000 gallon IG Plaster Pool.
    Hayward Northstar 2HP pump.
    Hayward Swim clear C4025 Cartridge Filter.

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    mas985's Avatar
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    Re: Is 6 PSI too low?

    Yes, air in the lid combined with low pressure is usually an indication of a couple of things.

    1) There is a blockage in the suction line which is causing the pump to suck in air.

    2) There is a blockage in the impeller which is preventing the pump from fully priming.

    Did you recently vacuum a lot of debris out of the pool?

    With the pump off, open the lid, remove the basket and reach in the inlet and see if there is anything stuck in there.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  10. Back To Top    #10

    Re: Is 6 PSI too low?

    Well I didn't find anything stuck in the inlet. I'm going to be calling the pool guy today for help as I am not confident enough to do anything else to the system at this point. Thanks for all the help though!
    ~20,000 gallon IG Plaster Pool.
    Hayward Northstar 2HP pump.
    Hayward Swim clear C4025 Cartridge Filter.

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