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Thread: PSI at Low speed

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    tcat's Avatar
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    May 2012
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    PSI at Low speed

    Just put in a 2 speed pump. On high my DE gauge reads 29 on low it reads 8. I have a 2# check valve in a 2" line going to the pool; on low it sits there and clicks and makes rushing sound (not loud, just noisier than the pump). Can I assume the check valve isn't really restricting flow? The reason pressure is 29 on high is I installed slotted return eyes and it raised that pressure by 5psi. Don't really care since I plan on running on low 8 hrs/day. Just curious what an expected filter pressure should be at low speed with clean filter.
    IG pebble, 15,000 gallon
    48 PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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    Re: PSI at Low speed

    I would suspect that you might have a bad pressure gauge. Does the gauge go to zero when the pump is off?

    Is the filter below the water level of the pool? If yes, how much?

    Why do you have the 2-pound check valve? Note: a 2-pound check valve will require 2 psi to get it to open.

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    JasonLion's Avatar
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    Re: PSI at Low speed

    I would expect the pressure to be even lower than that on low speed. The check valve is the most likely cause. Spring check valves are not ideal when using low speed.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    tcat's Avatar
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    Re: PSI at Low speed

    I have a 2# check valve because it came with the house and just had a single speed motor last week. If the filter is at 8#, the check valve must be open (4 jets have decent flow). I just thought the noise was funny and wondered what "normal" is on low. Pump is 6-8" above water level.

    Since pump is above, I see no reason for the check valve, may remove it, since 2# is restricting flow slightly.
    IG pebble, 15,000 gallon
    48 PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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    tcat's Avatar
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    Re: PSI at Low speed

    Also, I have an issue with skimmer function (on low). I have drain valve shut halfway, and skimmer still doesn't have much "suck". I can put a leaf 3" into the skimmer opening and it will float back into the pool. Most small bugs just float by (1" from it). It has rained and level is about 1" above center, but I don't think lower would help much. Is this normal?

    I ordered a Poolskim to hopefully alleviate the skimming problem. Will remove check valve tonight if I make it to Home Depot.
    IG pebble, 15,000 gallon
    48 PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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    Mod Squad jblizzle's Avatar
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    Re: PSI at Low speed

    Do you have a weir on the skimmer?
    Close the drain more.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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  7. Back To Top    #7
    tcat's Avatar
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    Re: PSI at Low speed

    Yes to the weir, normally works well on high. I guess I could close the drain and aim the jets straight down. Will try that tonight to see how much the skimmer improves.
    IG pebble, 15,000 gallon
    48 PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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