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How to Correct Low Water Pressure in Your Pool System

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Low pressure is a pool term that is often used to describe weak jets as well as a low PSI reading on the filter’s pressure gauge. High PSI readings will also cause low water pressure. A low or high PSI reading is anything outside the normal operating pressure of the filter. Weak jets, air bubbles, slow pool cleaners and weak water features are obvious signs of low pressure. This guide addresses the common causes of low water pressure in a pool.



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Step 1

Your pool’s plumbing system can be broken into two sections: the Suction-Side and the Pressure-Side. The Suction-Side of your pool includes the skimmer, main drains, plumbing, and any other equipment like diverter valves, up to the strainer housing of your pool pump. The Suction-Side is the portion of the system, your pump is pulling the water toward it. The Pressure-Side of your pump begins at your pump’s impeller; this is when the pump’s pulling becomes a pushing force to move the water through your pool filter, heater, chlorinator, and all the associated plumbing until it returns to the pool via the return jets.

Step 2

Low Water Level (Low PSI) - The water level should be at least halfway up the skimmer door opening. A low pool skimmer water level will allow the skimmer to gulp air as your water ebbs and flows caused by the pump running or activity in the pool.

Step 3

Clogged Skimmer Basket (Low PSI) - If your skimmer basket is full of debris, you are effectively shutting off the pipe between the skimmer and the pump. Generally, this will reduce the flow of water to the pump. If the pump has less water entering it, it is moving less water out. This means the pump is doing less work that in turn will reduce water pressure.

Solution: Clean your skimmer basket by removing any debris.

Click Here to View Replacement Skimmer Parts

Step 4

Clogged Strainer Basket (Low PSI) - It is the same story as above. A clogged strainer basket means less water flow that leads to less water pressure out the returns.   

Solution: Clean your strainer basket by removing any debris.

Click Here to View Replacement Pump Parts

Step 5

Clogged Filter (High PSI) - Again, if water can't get through a clogged filter, you will have less water flowing out of the filter. Incidentally, this will increase the water pressure in the filter signaling that it is time to clean the filter.  

Solution: Wash your cartridge filter. Periodically soak the filter overnight in a TSP solution to get the grease and gunk out of the folds. Grease is produced by suntan lotion, sebum (oils secreted by the human body) and pine tree needles. Then soak the cartridge in a weak solution of muriatic acid (10:1) to get the minerals out of the folds. Use the TSP before the acid or the gunk will set up in the folds. For sand filters you will need to backwash as required. Change the sand every five to seven years. In between changes, if sand has caked on top, take one to two inches off at the top and replace it with new sand.

Click Here to View our Liquid Filter Cleaner

Click Here to View Replacement Filter Cartridges

Step 6

Clogged Impeller (Low PSI) - This problem is often overlooked. If the impeller becomes clogged with debris, water can't rotate out the sides of the impeller. This decreases suction which reduces water flow through the pump.  

Solution: Clean out the impeller. See our guide on "How To Clean Out a Pool Pump Impeller".

Click Here to View Replacement Pump Parts

Step 7

Suction Leak At Pump (Low PSI) - The pump lid o-ring, pump intake fitting, and drain plugs are common areas to draw in air. A suction leak in the suction side of the pump can cause a number of problems. If it's large enough, too much air will be sucked into the system, and the pump will lose prime. If it's smaller, air will be sucked in through the pump and start to collect at the top of the filter tank. After some time (sometimes a few hours) air pressure at the top of the tank will create enough back pressure to reduce the flow of water significantly. When the pump is shut off, this back pressure will cause the water in the suction pipe to surge back and sometimes create a column of water up though the skimmer.  

Solution: Find the suction leak and close it. See our guide on "How to Identify and Correct Air Leaks".

Click Here to View Replacement Pump Parts

Step 8

Suction Leak at Diverter Valve (Low PSI) - The diverter valves in front of the pump control the flow of water from the skimmer, main drain, and vac lines. They also have seals in them that can go bad and allow air to enter the system. Again, air will cause the water pressure to drop and will lead to the pump losing prime.

Click Here to View Diverter Valve Parts

Step 9

Suction Leak At Plumbing Fittings (Low PSI) - Any fitting on the suction side of the system can draw air. Cut out and replace any fittings that have an air leak.

Step 10

Clogged Pipe Going To The Pump (Low PSI) - A clogged pipe from the skimmer, suction line or main drain reduces the amount of water to the pump which can reduce water flow to the pump and create low water pressure out the return lines.  

Solution: Push a stiff wire down the skimmer or suction ports to see if you have a clog near the entrance. If there are no clogs there, you may have to get a pool professional to come in to check your pool pipes.

Step 11

Too Many Features Opened - The pump is only designed to move so many GPM. Too many water features are like too many hoses on a sprinkler system. The first one has great pressure. Subsequent hoses will reduce the water pressure.

Solution: Alternate which features are turned on or replace the motor in your pump with a larger one. Make sure your existing filter will support the larger pump. You may also have to replace it.

Step 12

Pump Is Too Small - If your pump's size was calculated for you initial pool system and you have added more equipment onto that system, you may have exceeded the pump's capability to supply the GPM that is now required. Also, if you have moved your pump significantly further away from the pool, which required more pipe, you may have increased water resistance in the pipes that exceeds the pump's capability.   

Solution: Replace the motor in your pump. Note you may also have to increase the size of your filter if it won't handle the increased GPM water flow. See our guide on "How To Replace the Motor on Your Pool Pump".

Click Here to View Replacement Pool Pump Motors

Step 13

Bad Pressure Gauge - Pressure gauges on top of the filter do go bad. Your apparent low-pressure reading may be due to a faulty gauge.

Solution: Replace the pressure gauge. See our guide on "How To Replace a Pool Filter Pressure Gauge on a Cartridge Filter".

Click Here to View Replacement Filter Parts

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(81 to 120 of 373)

 Posted: 5/16/2019 

Hi - just opened pool and getting green water clear again. In the process of course there are many backwash cycles when the pressure rises. This year something different is happening with my (sand) filter. It holds a steady pressure of 20 as usual. The pressure never rose after hours of running - instead it eventually went down to 18. I then backwash and it goes back to 20 unit it I guess is dirty after some time and drops to 18. The reverse is happening from what is normal and what always happened in prior years. Why would it go down when dirty ?
 Reply

InyoPools Product Specialist  Posted: 5/16/2019 

Hello Paul - It's possible that the pressure gauge is bad. It's also possible to have a small air leak that slowly reduces the pressure in the system.
 Reply

 Posted: 5/11/2019 

My pump will backwash and rinse but won’t circulate water to pool and back thru pump!!
 Reply

InyoPools Product Specialist  Posted: 5/13/2019 

Is this a sand filter? If so, how old is the sand?
 Reply

 Posted: 4/27/2019 

I just installed new sand filter and pump. Pump runs, but I have no pressure reading at all on the gauge. It is zero. There is water coming out the return hose, but zero on the gauge.
 Reply

InyoPools Product Specialist  Posted: 4/29/2019 

The pressure gauge may be broken; they can be fragile. Contact the company from who you purchased the filter to get a replacement, or pick one up at a local hardware store.
 Reply

 Posted: 4/24/2019 

Have trouble with suction in my skimmer, jets still work but no water suction in skimmer. Check for any clog there is none. What could be causing this? Went through all your steps and nothing’s working. Please help.
 Reply

InyoPools Product Specialist  Posted: 4/24/2019 

Hello Nikki - If the jets are working normally and the skimmer is not working, my guess is that a valve has closed the skimmer line. It must be pulling all the water from the main drain. Try opening up the valve that controls the skimmer. You may need to close the main drain slightly in order to increase the suction to the skimmer.
 Reply

 Posted: 4/17/2019 

My pool guy just replaced the sand in my filter. Now the water pressure coming back in to the pool is real low. Also I noticed that the clamp ring that holds the head to the sand tank is now split on one side and I hear bubbles in the filter. would those have something to do with the low pressure? Thanks
 Reply

InyoPools Product Specialist  Posted: 4/17/2019 

Hello Bob - We'd be glad to assist you. Do you see air bubbles inside of the pump lid? Are bubbles coming back through the return jets? What is the PSI reading on the filter gauge (if you have one)?
 Reply

 Posted: 4/15/2019 

Went through all the steps above, none of those were the problem. My lovely wife bought a skimmer filter that was too small. Replaced it with the right one and immediately water flow returned.
 Reply

 Posted: 3/31/2019 

My pump works fine for 5 to 10 minutes, PSI gauge is at 18, then the return flow to the pool gets greatly reduced, the PSI gauge stays the same of might occasionally go up to 20. What do you think is wrong?
 Reply

InyoPools Product Specialist  Posted: 4/1/2019 

Have you completed any of the troubleshooting or checked points of concern mentioned in the article?
 Reply

 Posted: 3/15/2019 

Hi thanks to your guide I have sorted out zero pressure problem, this was due to junk that had built up in the pipe just before the pump cage as the mesh holes in filter cage too small to allow the larger bits of rubbish in, I removed the cage basket and pulled a big wad of junk from the pipe! Thanks a bunch as you saved me the cost of a pool repair call out.
 Reply

InyoPools Product Specialist  Posted: 3/15/2019 

Thank you for the feedback, Colin!
 Reply

 Posted: 10/13/2018 

Hi inyo, I've just installed a Davey Powermaster eco 3 speed pump. It's working beautifully. On high and mid speeds the pressure reads normal, but drops to 0 for eco mode. There's still a reasonable stream coming from the jets, and no air building up in the strainer housing. Should I be concerned about this, or will this just be normal for eco mode? Thanks again for all your help!
 Reply

InyoPools Product Specialist  Posted: 10/17/2018 

Hello Graham - It is normal to see 0 PSI when the pump is running on it's lowest speed. Your system is ok if you see movement through the filter, pump, and return jets. Heaters and salt systems likely won't work on that eco mode since those items require a certain flow rate that you probably aren't producing.
 Reply

 Posted: 9/25/2018 

Hello Maxxwell - The pressure usually rises that quickly because the pool is cloudy or the filters need to be soaked in a filter cleaner or replaced.
 Reply

 Posted: 9/24/2018 

Hello, any advice on how to diagnose the PSI pressure to rise to 25PSI only after 5 hours of cleaning the filters? I cannot figure it out. thank you in advance
 Reply

 Posted: 8/16/2018 

Hello dman4227 - We recommend reading our article titled "Why Are My Pool Jets Not Working". It has a number of solutions for resolving your low-pressure issue.
 Reply

 Posted: 8/15/2018 

Hello Texasney - Check out our article titled "Why Are My Pool Jets Not Working". Specifically, Part II of the article. This covers high PSI and low water output.
 Reply

 Posted: 8/14/2018 

Hello Tom - What happens if you set the filter to normal filter mode and hook up the vacuum hose? if it loses strength then i would say there is an issue with the hose. Suction hoses are susceptible to pinhole sized leaks that can trap air in the system causing drops in pressure. To test it another way, set the filter to waste without the vacuum hose attached to see the outcome. The first method I mention will save you money on water, I'd choose that one.
 Reply

 Posted: 8/10/2018 

My inground filtration function works just fine but when I set it to vacuum to "waste" setting and try to clean the pool out, it only has a very little suction power and isnt sufficient to clean the pool. Where might the problem be ? Thank you
 Reply

 Posted: 4/2/2019 

Skimmers have low pressure .when turned on get air at pump . Main drain an vac seems to be ok. Did not have this problem before winterizing , but was low when I reopened pool. Thanks
 Reply

InyoPools Product Specialist  Posted: 4/8/2019 

First question Roger, of the troubleshooting tips mentioned in the guide, which have you completed?
 Reply

 Posted: 4/8/2019 

I have tried them all
 Reply

InyoPools Product Specialist  Posted: 4/9/2019 

If you've truly gone through all of these, then it would be time to bring in a professional to diagnose it. The things listed are pretty much everything that could affect the flow rate of the pool. If your problem is persisting, then there is an anomaly that needs further looking in to.
 Reply

 Posted: 8/8/2018 

Thank you. Pressure in filter strong. Outflow decreases and stays weak w/ filter in.
 Reply

 Posted: 8/8/2018 

Hello Texasney - When you say that the pressure is low, do you mean that the pressure coming out of the jets is low or that the pressure reading on the filter gauge is low?
 Reply

 Posted: 8/5/2018 

Pressure way down. Took out cartridge filter. Ran w/o filter. Perfect! Stayed perfect for hours. Cleaned filter and re-inserted. OK at first, but pressure gradually dropped again. Your thoughts.....
 Reply

 Posted: 7/18/2018 

Hello Charlene - There may be a plug on your filter valve that can be removed. That is where you would thread in a pressure gauge.
 Reply

Anonymous  Posted: 7/9/2018 

my problem is when I start my pool I have good suction but lose it over a short period of time. When I quickly backwash filter and then return to normal use, I have suction again. Cycle follows. I used a shop vac to blow the skimmer lines but the problem remains.
 Reply

 Posted: 6/26/2018 

Just want to thank you for your video to trouble shoot, "Low pump water pressure". Turns out I needed to clean out debris in my impeller...never would have focused on that without your video...many thanks!!
 Reply

 Posted: 6/7/2018 

Hello Damion - If the water is not clear, the filter may be filling up quickly and that is why the PSI rises and the jets slow down. If the water is clear, there is something wrong with the filter. This could be the sand or laterals. Check out our article titled "Why Are My Pool Jets Not Working".
 Reply

 Posted: 5/30/2018 

So... I have LOW water pressure. I have tried everything you have suggested. The thing is, when I put the filter to recycle, I have the pressure I would love to see. When the filter is running I have 20 psi and a trickle coming out to the pool. I have tried blowing the line, checked for air leaks, changing the sand, getting a new pump... (insert hysterical scream)! What am I missing? Please help. What am I doing wrong?
 Reply

 Posted: 5/22/2018 

We opened our pool over the weekend and primed the pump system. However, same as others posted, the system will not maintain the suction when on filter, or when vacuuming, with lots of air bubbles. I'm going to try the suggestions in this post first. My mom gave me this system (worked last year) but it does not have a pressure gauge so I am curious if one can be installed on a sand filter that did not come with one?
 Reply

 Posted: 5/18/2018 

Are you plugging the hose directly in the hole at the bottom of the skimmer or are you using a vac plate? Do you have an above ground or inground pool? What is the PSI reading on the filter pressure gauge when the vacuum loses suction?
 Reply

Anonymous  Posted: 5/17/2018 

We have tried all of these things and are still having trouble with it maintaining suction when vacuuming (just with vacuuming). The vacuum will go good for about 2 minutes then it completely loses suction. We have replaced o-rings and cleaned everything out and have no idea what to do next.
 Reply

 Posted: 5/17/2018 

Hello Andrew - That second hole in the skimmer does lead to the main drain. There is usually a float valve or flapper that controls the suction to the main drain on that hole. However, plugging that hole would not correct your problem. Try using a vac plate instead of plugging the vacuum hose directly into the skimmer hole. This way the pump would still be able to have the flow from the main drain and it will hopefully receive enough water.
 Reply

 Posted: 5/14/2018 

Well, I don't seem to have a diverter valve. I have one line only above ground going into my pump. There is a valve on that just before the pump. I have played with it a bit, but I figure that closing it would stop all water flow entirely. I am plugging my vacuum hose directly into the suction hole in the skimmer. I have a second vacuum (Barracuda) with its own hose, and they both have the same problem, so I don't think it is the vacuum hose that is drawing in air. There is a second hole in the skimmer with no suction (I think that goes to the main drain?). Should that hole be covered? There is no suction problem in my system at all when the vacuum hose is not plugged in, and I don't lose any water in the pool. Thanks!
 Reply