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How to Correct Low Water Pressure in Your Pool System

WRITTEN BY: Inyo Pools

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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.

Step by Step

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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

Comments

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(1 to 40 of 373)

Dean Posted: 1/31/2022

Pentair Intelliflow VS 3hp pump with cartridge filters running 1400 rpm 24/7. 17,500 gallons. Aqua Jet pressure sweep with booster pump, but no other features. With cartridge filters clean, zero pressure on the filter gauge unless the rpm is increased to 2400 rpm. True for 4 years and two gauges. Pool is clear and clean routinely and return pipes produce ripples. Why no pressure reading when at 1400 rpm even when filters are 3 months dirty? Thank you for any advice.
Reply

InyoPools Product Specialist Matt S. Posted: 2/1/2022

A variable speed pump's flow rate is dependent on the feet of head of the system. The 1400 RPM setting on pool A could mean 25 gallons per minute, while it is 10 gallons per minute on pool B. If your pump's output is on the lower end of that, and you have a mid-sized or large cartridge filter, the pump's flow output is not going to be enough to move the needle. When you increase the RPM, the flow rate increases, which causes the pressure gauge to move. If this pump schedule is working, there's no reason to change it.
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Shona Posted: 10/22/2021

I have just put a heat pump on and have noticed that the pool vacuum (pentair great white 2) isn’t getting enough suction to climb the walls anymore. I’ve tried everything (including a new great white which made no difference) and ended up thinking the loss of suction has to be related to the new heat pump somehow (like less suction because the water is going through more things? I dunno). But after reading this I’m thinking the vacuum works on the suction side of the pump, the heat pump is on the pressure side of the pump right? Therefore the heat pump can’t be the reason that the vacuum isn’t getting enough suction?
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InyoPools Product Specialist Matt S. Posted: 10/25/2021

Is your pool pump a single speed, or is it a variable speed? If it is the latter, did the RPM levels get changed when the heat pump was installed? Sometimes installers will lower the flow rate to give the water more time in the heat exchanger.I'd check that the cleaner's skirt and brushes are in good condition. Also, the cleaner's flow regulator may need adjusting
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Scott Posted: 10/20/2021

I have just put a heat pump heater in my pump has run for a couple of days , went to put my creepy crawly on and there is next to no suction. Have checked baskets, impeller, pulled pump apart , changed spider gasket due to a leak and looked for leaks in suction side still can’t find anything. Pool is clear and seems to pump fine Any ideas
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InyoPools Product Specialist Matt S. Posted: 10/20/2021

What model of Kreepy Krauly is this? Is it a suction-side or pressure-side cleaner? Kreepy Krauly has become kind of an all-encompassing term like Xerox. Some pool owners call all pool cleaners Kreepy Kraulys, so I want to be on the same page.If it is a suction cleaner, check the hoses for pinhole air leaks. A couple of those air leaks can be just enough to prevent your pump from priming or rob the cleaner of its suction power.
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Mark Metzger Posted: 9/21/2021

Great site and info. Just purchased a new home with a pool/spa setup. I have an Intelliflow variable speed pump. There are separate returns for the skimmers vs bottom returns. No matter how I have the valves turned, the skimmers are barely pulling water. The sand filter reads 6psi and doesn't really change at all. I would assume that if the filter was causing the low flow that the pressure would be quite a bit higher. Therefore, I'm thinking something with the returns or pump. With so many returns, if one was clogged, the others should still be grabbing water but that is not the case. So in the end, I'm think the pump. There is some limited air at the pump filter cover but it doesn't look like an air leak. How can one tell if the impeller itself is bad? I would think this pump should be really pulling water. Please help, I am really puzzled. Mark
Reply

InyoPools Product Specialist Matt S. Posted: 9/22/2021

Thank you for reading! Before you check any of the other stuff, review the IntelloFlo pump's run schedule and RPMs. As you said, it is a variable speed, and VS pumps are usually set to lower RPMs to increase energy savings. You may be confusing the low speed of the VS for a pressure issue.
Reply

Mark Metzger Posted: 9/22/2021

Thanks for the reply. I’m running at 3100 rpm. When I dial down to 1700 there really is no skimmer movement. I played with it last night and completely shut off the floor intakes. Got a nice vortex on one skimmer and slight on the other. I may run a line on the slower skimmer to check for some blockage. The run isn’t very different between the two so don’t understand why there would be such a difference. I think I’m asking too much of this setup. Don’t see how it could do much if I had both skimmer and floors intakes wide open. The skimmer baskets are high efficiency types so maybe that matters.
Reply

InyoPools Product Specialist Matt S. Posted: 9/23/2021

The skimmers and main drain are suction lines; the return lines are what bring the water from the pump/filter back to the pool. If you have all the suction lines open, it is going to disperse the suction power among the three lines. I don't know if you have a 3 HP or 1 HP Intelliflo, but if you have the 1 HP, it would explain why the flow is on the low end. Variable speed pumps are meant to be set at lower speeds to increase energy efficiency, so you usually wouldn't see the telltale drain vortex during a regular cycle.Sidenote on the skimmer, If the skimmer closest to the pump has the stronger suction, that would be normal. It likely has a shorter run.If you believe there is a problem with the system, go through the steps for troubleshooting. Since you are new to pools, I wouldn't presume anything on sheer observation without testing the various parts of the system. I can throw out many guesses, but nothing gets solved until you start checking the system in the manner we layout above.
Reply

Joseph Nichols Posted: 8/9/2021

I can't figure out my low flow situation on my xtreme hayward cartridge filter w/ 1.5HP hayward pump. I have a hayward heater attached to the system that won't work because of low flow. all joints and hoses are good. skimmer baskets emptied. water level good, even cleaned the propeller in the pump . New cartridge was put in at the beginning of this pool season. i pull the cartridge, clean it with a hose, put it back in, and the system runs fine for 24hrs then back to low flow. I just can't figure it out and its getting really frustrating. Please help
Reply

InyoPools Product Specialist Matt S. Posted: 8/11/2021

Have you tried giving the cartridge a deep cleaning (acid bath)? If your filter is a couple of seasons old, cartridges eventually get so gunked up that regular old spraying downs don't work. An acid bath will clear the deepest nooks and crannies in the pleated fabric.
Reply

Elizabeth Perillo Posted: 7/19/2021

After I do a backwash jets are working perfect. As the day progress pressure gets weaker and weaker. Then I do a quick backwash and good again.. However having to do this on the daily. What is causing this?
Reply

InyoPools Product Specialist Matt S. Posted: 7/20/2021

That is covered in the guide, step 5: chemically soak your cartridges or grids
Reply

LISA S Posted: 7/14/2021

we just replaced our de to a sand filter, replaced the motor with a two cycle one, new vacuum hayward with the two wheels. All at te recommendation of our new pool service. Drained the pool, scrubbed the sides and still not enough pressure to move water or vac. Keep on telling my pool guy we don';t have enough pressure. what can I do? is it the new motor?
Reply

InyoPools Product Specialist Matt S. Posted: 8/4/2021

Since it is dual speed motor, are you running it at high or low speed? Most dual-speed motors are scheduled to run at low speed mostly. If you want to vacuum, you must manually change the speed to high RPMs at the timer or switch.
Reply

Bob Posted: 6/15/2021

Can a pump be moving water but still have low pressure? My gauge is showing zero but I have circulating water. Also, the heater is showing flow error..
Reply

InyoPools Product Specialist Matt S. Posted: 6/17/2021

If the pump is moving water, the system should show some pressure reading. Have you tried cleaning the filter?
Reply

Amanda Posted: 6/3/2021

Just replaced our Hayward S220t sand filter. It seems to run fine when first started but over a few hours the PSI increases and flow decreases. The heat pump flashes no flow and no flow will eventually illuminate on AquaRite. The water is always clean during the backwashes. We are also picking up sand in the pool cleaner. Everything else seems to be functioning normally. Any suggestions?
Reply

InyoPools Product Specialist Matt S. Posted: 6/4/2021

Did you replace the sand filter with the same fixed filter tank? If it was a smaller-sized filter, it would explain the excessive clean cycles. Is your water clear or are you dealing with cloudy or green water?
Reply

poolman Posted: 6/2/2021

Will a leak in my return pipes (after filter) cause low pressure?
Reply

InyoPools Product Specialist Matt S. Posted: 6/4/2021

I guess it would depend on how big the leak is; is it pouring or dropping? Either way, a leak isn't good and it should be sealed up. But chances are the leak isn't big enough to cause a drop in pressure.
Reply

Mark Posted: 5/13/2021

Getting a low flow error from Hayward heater, I noticed the pressure in my filter was high as well, so I removed filters and chemically cleaned. Reinstalled and everything worked fine for 24 hours, then same error. I removed the filters and ran system without filter media, no error from heater. My filters are only 2 years old and in good condition but my pump is 10 years old, Hayward tristar sp32005ee. Good my pump be bad how can I test my pump?
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InyoPools Product Specialist Matt S. Posted: 5/14/2021

It is not your pump it is your cartridges. The system slows down after 24 hours use post an acid soak, and the pump runs fine with the cartridges taken out. The problem is the cartridges unless you are already dealing with green or cloudy water that is clogging the cartridges quicker than normal. If it was the pump, your system wouldn't be working with the cartridges taken out.Old cartridges can be soaked, look clean, and still be chocked full of years of debris. This is why eventually chemical soaks are no longer effective and you just have to get new cartridges.
Reply

Anonymous Posted: 5/14/2021

Thx Matt, my plan was to trying to locate replacement filters today and test that theory as that is what I was leaning towards too.
Reply

?? Posted: 4/27/2021

We just opened the above ground pool and after a couple of hrs of filtering the pool loose pressure and after back wash it works right for a couple more hrs do anyone have any ideas whats happening
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InyoPools Product Specialist Matt S. Posted: 5/13/2021

Is your water clear, cloudy or green? If it is the latter two, you are having pressure issues because whatever is making your water murky is clogging the filter quickly after you clean it. Guides that might help: How To Go From Cloudy To A Crystal Clear Pool & How to Clean a Green Pool?
Reply

Ken Posted: 4/14/2021

I have a separate pump for a waterfall and after it runs for about an hour the water flow reduces to a very slow trickle of water. Why does the water stop flowing after an hour running?
Reply

InyoPools Product Specialist Matt S. Posted: 4/16/2021

It could be any of the things we show in this guide, besides the filter if it is a standalone pump setup. Have you done any troubleshooting we mention above? That'd at least narrow down the field of possibilities for us to consider.
Reply

Dave Posted: 4/9/2021

I have a salt water heated pool and the Raypac heater keeps shutting off and restarting .The error code is HP6 . Filter and skimmer were just cleaned .PSI on the filter is 20 .
Reply

InyoPools Product Specialist Matt S. Posted: 4/16/2021

This was listed in the manual concerning the HP6 code: "Low water flow in the unit or faulty high-pressure control. Check water flow/backwash. The unit will show (HP6) after 6 HP faults. This will stop the unit for protection."What is the model number of your pool heater? I can try to find a replacement high pressure control.
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David Posted: 4/16/2021

Its a RAYPAK R8350TI-E
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InyoPools Product Specialist Matt S. Posted: 4/21/2021

You have a high-pressure fault. This is the part, we currently do not stock it, though High Pressure Control kit H000015
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Sebastian Posted: 3/23/2021

I have DE filter 24 ft² . I just had the gaskets replaced to my pump. I keep losing prime in my pump after an hour or 2 of running the pressure gets up to 30 in my filter. Filters are brand new less then a month old .
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InyoPools Product Specialist Matt S. Posted: 3/23/2021

There are quite a few things mentioned in the guide to check besides the pump gaskets. Did you check the water level, valves, unions, and plumbing joints for sucking air leaks? Another helpful guide you should read: How to Find Suction Side Air Leaks In A Pool
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Shea Posted: 8/17/2020

I have pressure when backwashing, rinsing.... but jets have very low pressure. Have cleaned cell, emptied skimmers and pump basket. Any other tricks???
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InyoPools Product Specialist Matt S. Posted: 8/24/2020

What type of filter do you have? Is it Sand or DE? if it is sand, how old is the sand? Old sand can reduce your system's pressure even after thorough backwashing.Another thing to try is to set the filter to "recirculate' to bypass the filter media to determine if the filter media is the issue or if you should be looking elsewhere.
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Naomi Posted: 7/29/2020

Hi, I Noticed my jet return is very weak. I have a DE filter and after I backwashes, the return is good for about 15 minutes then weak again. I cleaned the skimmer and pump baskets .And I fixed my water level as well. Any other ideas?
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InyoPools Product Specialist Matt S. Posted: 9/8/2020

What is the model number of your filter, and how much DE are you adding after a backwash?
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Jen Posted: 7/22/2020

Skimmer was replaced and a "rubber boot" was used to connect the pipes. Now the PSI is low and the pump will not hold prime. Could the connection have collapsed to cause this?
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