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Thread: Pump losing pressure now and then

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    botanica37's Avatar
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    Pump losing pressure now and then

    Twice in couple of weeks my pump goes from 13 PSI to 0. The first time it was when the pump started in the morning, tiny amount of water in pump's skimmer basket. Clean everything, turned it on and off couple of times and it went back to normal.

    Second time, it was fine, I switched it off to backwash the filter, did that, switch the filter back on and started the pump. 0psi, almost no water coming in the pump. Turned it off, disassembled the pump, cleaned everything, checked the o-rings, impeller?, checked o-rings on the skimmer, everything was fine. Just to be safe, replaced the o-rings on the skimmer. Turned it on, no pressure. Changed the suction from pool to spa,no difference, still tiny trickle of water. Went back and forth couple of times, somehow after a while, it worked, PSI went back to normal, but there were some air bubbles in the basket.

    Couple of days later, bubbles gone, 2-3 days later, some bubbles. What is going on? The pool guy says that I have a cracked pipe under the deck (from all the trees collapsing in the pool a month ago) and wants to do a pressure test ($$$). It doesn't make sense to me that both pool and spa pipes are cracked and that the problem will come and go. Leak is a leak, right? It doesn't self repair, so I don't see why the pump will work one day and not the other?

    Any thoughts would be greatly appreciated.
    free form 40k gal, IG, plaster, Triton II 100C sand filter, Lite 2 heater
    1 1/2 HP Pentair Ultra Flow High Performance pump
    Caretaker in-floor cleaning system

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump losing pressure now and then

    It sounds like a sticking weir but that probably woudn't happen to both the pool and spa.

    It's probably an air leak near the pump. If it's a valve seal it could come and go. Even if it's the pump basket o-ring or drain plug it could seal itself at certain times and leak at others. Though that's odd.
    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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    mas985's Avatar
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    Re: Pump losing pressure now and then

    When the pressure starts off at 0 PSI, is the flow rate out of the returns reduced significantly?

    If not, it could just be stuck pressure gauge. Next time it happens, tap on the gauge and see if it jumps up.

    Otherwise, there is probably an air leak somewhere.
    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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    botanica37's Avatar
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    Re: Pump losing pressure now and then

    Could that be the Jandy valve? I think the one thing i can't figure is that when the issue is present, it doesn't solve by switching between pool and spa, and these are two separate lines with two separate valves. So if there is a leak, it should be in the 2 ft section that leads to the pump, but i can't seem to isolate the leak.

    That aside, do you feel that pressure testing would be a waste of money and time?
    free form 40k gal, IG, plaster, Triton II 100C sand filter, Lite 2 heater
    1 1/2 HP Pentair Ultra Flow High Performance pump
    Caretaker in-floor cleaning system

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    Mod Squad Bama Rambler's Avatar
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    Re: Pump losing pressure now and then

    Can you post a pic of the pad?

    I'd do some more investigating on my own before I got it pressure tested.
    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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    botanica37's Avatar
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    Re: Pump losing pressure now and then

    Here are couple of pics, hope it shows enough. Thanks!
    Attached Images Attached Images
    free form 40k gal, IG, plaster, Triton II 100C sand filter, Lite 2 heater
    1 1/2 HP Pentair Ultra Flow High Performance pump
    Caretaker in-floor cleaning system

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    mas985's Avatar
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    Re: Pump losing pressure now and then

    Quote Originally Posted by mas985
    When the pressure starts off at 0 PSI, is the flow rate out of the returns reduced significantly?

    If not, it could just be stuck pressure gauge. Next time it happens, tap on the gauge and see if it jumps up.

    Otherwise, there is probably an air leak somewhere.
    You never answered my question.
    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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    botanica37's Avatar
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    Re: Pump losing pressure now and then

    I am sorry, I didn't check the flow rate out of the returns and since the issue is intermittent, I don't have a way to duplicate the problem and check. The pressure gauge is definitely not stuck, because I tapped it a lot and it didn't move. My concern is that there was almost no water flowing in the pump basket, regardless of whether the valve was on pool or spa.
    free form 40k gal, IG, plaster, Triton II 100C sand filter, Lite 2 heater
    1 1/2 HP Pentair Ultra Flow High Performance pump
    Caretaker in-floor cleaning system

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    mas985's Avatar
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    Re: Pump losing pressure now and then

    Quote Originally Posted by botanica37
    My concern is that there was almost no water flowing in the pump basket, regardless of whether the valve was on pool or spa.
    Does this mean there is air in the pump basket? In other words, how can you tell there is no water flowing in basket? Normally, when the pump basket is full of water without any air bubbles, it is very difficult to tell if water is moving or not. However, if there is air in the pump basket, then I understand.

    Also, once the pump is working properly and running, does it ever lose pressure while it is running or does this only occur on first start?

    Next, the brass valve after the 3-way and before the pump, is that a check valve? Have you removed that and made sure it is working properly? If broken it can periodically block the flow and create the symptoms you are seeing.
    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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    Mod Squad Bama Rambler's Avatar
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    Re: Pump losing pressure now and then

    Mark, good point about the brass check valve. I've seen those hang up more than once.
    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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    botanica37's Avatar
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    Re: Pump losing pressure now and then

    Mark, to answer your questions:

    Yes, there is air in the pump basket when it happens. A lot of air, and I can see through the plastic that the water is trickling in.

    Once up and running, the pump doesn't lose pressure, it only happens on start or after backwashing. Also, since that happen the first time, I do get the small air bubble you see in the picture there almost all the time. I also see tiny bubbles coming from the returns.

    I have no idea what the brass valve does, or if it is a check valve. I have not removed/open that, but i am going to HD right now to get the proper size wrench and will let you know what i find.

    thank you!
    Ioana
    free form 40k gal, IG, plaster, Triton II 100C sand filter, Lite 2 heater
    1 1/2 HP Pentair Ultra Flow High Performance pump
    Caretaker in-floor cleaning system

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    Re: Pump losing pressure now and then

    Quote Originally Posted by botanica37
    Mark, to answer your questions:

    Yes, there is air in the pump basket when it happens. A lot of air, and I can see through the plastic that the water is trickling in.

    Once up and running, the pump doesn't lose pressure, it only happens on start or after backwashing. Also, since that happen the first time, I do get the small air bubble you see in the picture there almost all the time. I also see tiny bubbles coming from the returns.

    I have no idea what the brass valve does, or if it is a check valve. I have not removed/open that, but i am going to HD right now to get the proper size wrench and will let you know what i find.

    thank you!
    Ioana
    That brass gizmo is a check valve. They don't fail often, however, when they do, the symptoms you describe are exactly appropriate. From your pixs, the only reason it needs to be there is if your equipment pad is significantly elevated above the pool (more than a foot or so...the valve keeps water from running back to the pool when the pump lid or filter is opened).
    If you really need a check valve, may I suggest a Jandy check valve (with a clear top), so you can easily tell if it's clogged or jammed
    In the industry, CSP (Certified Service Professional) by the NSPI and it's successor the APSP. My company services over 600 pools every year. I think the practices regularly espoused on this forum (especially the BBB method) are outstanding; however my comments will be often oriented towards the goal of getting it done, and getting it done right now!

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