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Thread: Filter pressure decrease by 3 psi

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    Filter pressure decrease by 3 psi

    just got back home from work and noticed the pump is quieter than before and I checked the filter pressure which was at 13psi. It was 15-16 yesterday. So there must be something abnormal. I cleaned the pump basket and put the pump back to work. The pressure is now at 15.5 psi. the basket has some pine needles, but I don't think flow was blocked. Is that possible the filter pressure drop is due to the dirt in the pump basket?

    Sorry a newbie and have questions almost every day. Thanks
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
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    Isaac-1's Avatar
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    Re: Filter pressure decrease by 3 psi

    I would tend to guess suction side flow restriction from the pine needles
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    Re: Filter pressure decrease by 3 psi

    Mine does that on occasion.

    Sometimes after the pump has been off for awhile it comes back on at a lower pressure, or if some debris is on the main drain or the skimmer basket has stuff in it, it will fluctuate.

    I never really thought about it being a problem.
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    Re: Filter pressure decrease by 3 psi

    Of course it may also be that the needle is sticking on your pressure gauge, most pool pressure gauges are about the lowest quality money can buy
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Re: Filter pressure decrease by 3 psi

    I also noticed there are always some debris covers main drain this week. Brush the debris away, but after a while the main drain was covered again. Not sure if they are related.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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    YippeeSkippy's Avatar
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    Re: Filter pressure decrease by 3 psi

    That just means your pool has debris in it that gets sucked up on to the main drain covers. Vacuuming can remove it, or brushing can help get it into circulation so that the small stuff gets down thru the skimmer and caught in the skimmer basket.
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    mas985's Avatar
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    Re: Filter pressure decrease by 3 psi

    Quote Originally Posted by shiyang100 View Post
    Is that possible the filter pressure drop is due to the dirt in the pump basket?
    Absolutely. Debris in the pump basket restricts flow (higher head loss = lower flow rates) so the when the flow rate decreases, filter pressure decreases. This is how you know you have a clog on the suction side of the pump.
    Mark
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    Re: Filter pressure decrease by 3 psi

    Thanks. I will keep monitoring the situation. Hopefully the cleaning of the basket is the culprit
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
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    Re: Filter pressure decrease by 3 psi

    A quick update. The filter pressure started at 16 psi, and it went down very slowly. Lost 1 psi every 2-3 hours. There is no air bubble under the pump lid. I am at lost now.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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    mas985's Avatar
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    Re: Filter pressure decrease by 3 psi

    Debris can clog the MDs and skimmer too and reduce flow. You mentioned before that the MD clogging. Do you have the skimmer line open or closed? The skimmer line should always be open. Also, make sure the skimmer basket is empty.
    Mark
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    Re: Filter pressure decrease by 3 psi

    Yes. I cleaned the skimmer basket almost every day. Both skimmer lines valves are open
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
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    mas985's Avatar
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    Re: Filter pressure decrease by 3 psi

    Then it could be debris collecting in the impeller. Remove the pump basket and reach inside the impeller inlet and see if you can pull out any debris. Pine needles can easily make it past the baskets.
    Mark
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    Re: Filter pressure decrease by 3 psi

    For the past several days, I have been cleaning the pump basket every other day. What I noticed is the filter pressure still went down, but only a little every day maybe 1/2 psi per day. Not much. I used the finger and didn't feel anything blocking the front of impeller. Is this the right way to check impeller blockage? Anything else could cause my problem?

    Thanks so much.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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    Re: Filter pressure decrease by 3 psi

    Yes that is the correct way to check for impeller inlet blockage but does not check for impeller vane blockage. The only way to check that is to pull the motor from the wet end so you can inspect the impeller directly.

    But if the pressure is only decreasing by 1/2 PSI, I wouldn't worry about it.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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    Re: Filter pressure decrease by 3 psi

    Thanks Mas985.

    the he pump I have is sta Rite single speed pump. I noticed recently that once the filter pressure is doe even by a couple of psi, the pump makes less noise. This gives me a feeling pump is not running to its max speed. I am worried if this 5 yr old pump is close to the end of life

    as as I mentioned several weeks ago the PB didn't close my pump lid properly while I was on vacation. So basically the pump was running with air sucked in for about a week. I am not sure if these two are related events.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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    mas985's Avatar
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    Re: Filter pressure decrease by 3 psi

    The less noise is probably due to reduced flow rate and as long as it isn't a lot, there isn't much to worry about. Also, if there was something seriously wrong with the pump, it most cases it should shut down on it's own.

    So basically the pump was running with air sucked in for about a week.
    Was it still moving water during this time? If it was so bad, the pump was running dry, then that could be an issue.

    Also, make sure the pump isn't leaking water anywhere. That can signify trouble.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Filter pressure decrease by 3 psi

    Learned a trick using clothing hanger to clean the impeller on the internet. Tried and couldn't get anything out.

    Another interesting thing I also noticed today. When pump was first on, the pressure seems to be normal and the pump noise was fine. After several hours, the filter pressure went down a little, a couple of psi and the pump sound got lower a little bit. Off a while, turn it back on, the pressure went back to normal again. Since the pressure difference is not that huge, I couldn't really tell the difference from the return jet.

    I really have no idea where to continue the troubleshooting.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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    Re: Filter pressure decrease by 3 psi

    Have you taken apart the filter yet? There might be something going on in there (e.g. loose or ripped cartridge).
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Filter pressure decrease by 3 psi

    No, I haven't touched the filter yet. Never thought it could be the problem.
    Massachusetts
    Vinyl Salt Pool 2011; IC40 SWG; Raypark gas heater; Sta-Rite Dynapro pump; Sta-Rite System 3 Filter S7M120; Pool size: app 25000 Ga
    first time pool owner. First year too.

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