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Thread: low pressure pump or other problem. Please I need help troubleshooting

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    low pressure pump or other problem. Please I need help troubleshooting

    Hi I am new to posting here, I have lurked off and on over the years. This is my third house with a pool. However, I hate this pool! When I initially bought this house my mother (picked it out and) lived in it and I didn't have to deal with the pool. Well now I live here and I don't know what to do.

    I have a 8K gallon fiberglass pool with two inlets, one skimmer, 1 main drain, and side suction for cleaner, with a navigator attached, pool was built in 2005. The pump housing was cracked when the home was purchased in 2008. At the time of purchase the pressure on the filter read about 8psi. I know she had the pump repaired many times over the years and I noticed it also has had the motor replaced. (she never maintained the pool or filters or baskets)

    Well the pump has been getting louder and the pressure has been really low the last 5-6 months. So I decided to just replace the pump. The pump that was there was a 1HP, s.f. 165. I replaced it with a Pentair whisperflo 1.5 HP uprated, sf HP 1.65. Everything started up great and the pressure started off at about 12psi on the gage. Over the next hour the pump gradually got as loud as the old pump and and the pressure had dropped down gradually where the last pump was at - down to barely 5psi.

    I took apart the filter, cleaned it again, lubed the o-ring, cleaned the baskets, lubed the pump basket, and turned it back on. The pressure again started at 10psi, but over the next hour it again dropped down to about 5psi with the pump being really loud. No screeching or anything just very loud operation.

    So I turned it off, as I turned it off I noticed the cartridge filter cover sink down. Maybe it has always done this but I never paid attention to it. I turned it on and off a few times and noticed it raises and drops with the power.

    Anyways I don't know what to do about this, I need some ideas of what I need to look at.

    The filter is a sta rite system II plm 150, max gpm 56, max psi 50, I replaced that filter about 1.5 years ago and it still looks in great shape. All the piping above the ground is 2 inches. I have no idea what is below ground, but the pump and filter sit about 10 from the return two return lines and about 30 feet from the skimmer.

    After that is a zodiac clear water salt cell, also newly replaced about 6 months ago.

    Can anybody help me with what I need to do? check? change or replace?

    TIA
    Michaelle

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    JasonLion's Avatar
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    Re: low pressure pump or other problem. Please I need help troubleshooting

    Welcome to TFP!

    I can't be certain, but that sounds like it is a slow suction side air leak. When the pump is running but not producing the correct pressure does the pump strainer basket get a lot of air/turbulence in it? If so, it is almost certainly an air leak. There is information on how to approach suction side air leaks in Pool School, see the link near the top right of every page.
    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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    Re: low pressure pump or other problem. Please I need help troubleshooting

    ty for the quick reply. The lid doesn't appear to have any more air/turbulence than I have seen in my other two pools, but shining the flashlight into it, I can see some air bubbles passing through. But without shining a light in there I wouldn't see it, as I didn't see any during the day. Turbulence? yes there is a leaf in there circulating around some.

    Does that sound like enough air and turbulence?

    Also now that it has been off for a couple of hours, the pressure is back up to 10. But it will slowly drop over the next hour.

    Okay I read through pool school and some other places on the web. When I turn the valve all the way to the skimmer I get lots of air and turbulence in the pump basket, and turning it to the suction cleaner I don't get that. So... tomorrow I'll be checking for an air leak around the jandy valve. - would that just need a new o-ring?
    Last edited by aneidabreak; 03-16-2014 at 01:00 AM. Reason: added info

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    mas985's Avatar
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    Re: low pressure pump or other problem. Please I need help troubleshooting

    When you say that you are turning the valve towards the skimmer, is the valve handle 180 deg away from the skimmer pipe? That would mean the skimmer is off and would explain why you are getting a lot of air. The cleaner port is sometimes a smaller pipe and would have a lot of suction head causing a lot of air to enter the pump basket. If the handle is pointed toward the skimmer pipe, then it could mean your skimmer pipe is clogged and needs to be cleared. That would also explain the pump noise which could be cavitation.
    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: low pressure pump or other problem. Please I need help troubleshooting

    When I open the skimmer all the way I am getting a lot of turbulence, and if I open to the sweeper side - makes the sweeper go faster - not so much. The valve is always left to favor the sweeper suction. And I have noticed that it seems like the skimmer doesn't suck as well at it used to. As stuff seems to stay afloat more and not sink into the basket. I have been pondering a clog in the skimmer line. But also didn't know if that old pump was failing again. Trying to remove the cover of the jandy valve right now. I cracked one before doing this, i'm trying to be delicate....

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    Richard320's Avatar
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    Re: low pressure pump or other problem. Please I need help troubleshooting

    It could just be as simple as low water level in the pool or a sticking weir (flapper) in the skimmer. Pull the lid and watch the skimmer awhile. Do you see a little vortex/whirlpool? Does the water level drop dramatically making it sound almost like a toilet flushing? Start with the simple stuff first. If it's not low water, then you may have an air leak somewhere. spray things with shaving cream. If the leak slows down or stops and the pressure rises, you've got a good clue to follow up. The foam will get sucked into the leak. Good luck.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: low pressure pump or other problem. Please I need help troubleshooting

    Okay, so replacing the o-rings in the jandy valve must have fixed an air leak there, as the skimmer is sucking like it should. And doesn't make the turbulence? that it was doing when opened all the way. So the pressure is back up now to 13. But it still is still slowly losing pressure over the hour and still gets louder. But it appears now to only go down to about 8 psi. but maybe I didn't wait long enough.

    Really everything looks really clear in the pump basket, I can see some bubbles pass through, but not anything excessive. Some of the debris in the basket will whirl around and stick, and maybe keep doing that. One air bubble at the top of the lid, that stays pretty steady, doesn't get bigger or move. The pool is still a little on the full side from some recent rain, i actually drained some out because there it was above the skimmer. so it is still about 2/3 up the opening. I checked the wier door and it is functioning properly. I don't hear any or see any kind of vortex in the skimmer, I removed the basket and watched for a while.

    I have slathered all the fittings on the suction side with shaving cream and I am having no luck. None of the plumbing is very intricate so there isn't much distance to cover.

    When I turn the pool off, It doesn't seem I even have to wait but a few seconds and when I turn the power back on the pump is quieter and pressure is back up.

    What is the difference between cavitation and turbulence?

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    mas985's Avatar
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    Re: low pressure pump or other problem. Please I need help troubleshooting

    Cavitation sounds like small gravel is traveling through the pump. This is caused by very high suction head which basically boils the water usually at the impeller. It is a very distinct sound. Here is a video of cavitation: http://www.troublefreepool.com/threa...itation-Videos

    Turbulence, is simply the chaotic motion of the water and is generally present in all pool plumbing and by itself is not a problem. However, you will only really notice turbulence when there is either air or debris in the water. The pump basket will normally have very turbulent water which is why you can normally see the debris moving about. The only issue is the air mixed in with the water. That can cause a reduced filter pressure and loss of both flow and suction.

    As for the filter pressure decreasing over time, you may still have a blockage in the suction line and when you shut off the pump, it pushes it back some and loosens it up. Just to make sure, I would try flushing the skimmer line backwards. Wrap a hose with a rag and put it into the line that enters the pump and force water backwards through the skimmer line. Remember to pull out the skimmer basket to see if anything comes out.
    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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