How to Reduce High Pressure in Your Pool System

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There are several high water pressure scenarios that come up and for one reason or another have no apparent solution. You just replaced a failing motor or pump and your pressure jumped up from 10 to 20. Or your pressure crept up from 10 to 20 due to a dirty filter. You sprayed the debris off you filter cartridge like you did 50 times before but this time the pressure remained high. Or every time you turn the pump off, the back pressure is so high that it blows the cover off the skimmer or pushes the vacuum hose out of the suction port. This guide discusses these scenarios and possible solutions to correcting them.

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Step 1

Why do I have high pressure? A pool system’s pressure is generally measured at the filter’s pressure gauge; the usual range is 10 - 25 pounds per square inch (PSI.) When you installed your filter, or after a thorough cleaning, make a note of the “clean filter” PSI. This rating will be used as a benchmark for pressure tests down the line.

High pressure is generated by three conditions: 
  1. The pump is pushing a higher water flowrate than the filter can handle efficiently.   is trying to move a larger flow of water (GPM) than it can handle; 
  2. A blockage after the filter is causing a bottleneck, creating backpressure inside the filter.    is a blockage (BLK) in the system after the pump - from the pump's discharge port. 
  3. A suction air leak before or at the pump is causing an air pocket inside the filter, which in turn creates the dreaded backpressure.
  4. Excessive plumbing creates backpressure as the water’s momentum gets slowed by every turn or rise in elevation it makes.

Step 2

Clean your Filter. The most common cause of high pressure in a pool is a dirty filter. Take cartridges as an example, as the material sives dirt from your pool water, the cartridge fabric more and more clogged. The clogging means the water has fewer and smaller perforations in the filter media to squeeze through. This creates a traffic jam of water, that presents itself at spiking PSI reading on the pressure gauge. Cleaning methods for each filter type:

  • Cartridge - Spray down cartridge for standard cleaning. For extra dirty cartridges, we suggest using a liquid filter cleaner. Click Here to View the Liquid Filter Cleaner
  • DE - Backwash thoroughly, open filter to hose down grids and remove any linger DE powder and debris in base of filter. The Filter Clean chemical can also be used to fresh up old grids.
  • Sand - Backwash thoroughly. If the filter sand is older than 5 years or shows signs of clumping or channeling, replace sand.

Step 3

Check your filter media - If your filter’s pressure is spiking after changing your filter media you may have fallen into one of these traps:

  • Sand - too much sand slows filtration of the water through the tank, creating backpressure
  • Cartridge - Replaced your cartridge with the incorrect size. Though a cartridge may be the same overall dimensions as your original cartridge, the square footage may be significantly less. Less surface area, makes for less flow, then to high pressure. Click Here to View Replacement Filter Cartridges
  • DE - Installing the wrong grid size. Or applying too much DE powder when recharging the grids. Click Here to View Replacement DE Grids

Step 4

Clogged Breathing Tube - Most filters have a breather tube to automatically purge air trapped at the top of the filter. This tube generally run from just under the top dome to the bottom of the tank. The breather tubes of some of the DE filters are integrated in the top manifold assembly and exit out through the discharge line. Air pressure in the top of the filter tank will build up if these breather tubes become clogged.

Click Here to View Replacement Filter Parts

Step 5

Oversized Pump - If your high-pressure reading has come directly after switching out your whole pool pump or pump impeller and motor assembly then you may have incorrectly sized the equipment. A pump’s flow rate is determined by its’ horsepower (HP,) whether it is a high or medium head style and the feet of head rating of PVC plumbing. If you jump up a HP, switch to a High head style from a medium head without accounting for feet of head differences then your pump’s flow rate could make a leap by 10 or more GPM. 
If your filter was already maxing out on the smaller pump, all that extra water has nowhere to go, and the rise in backpressure begins.

Correcting an oversized pump:
  • Replace impeller with a lower HP version to lower the GPM output. This is by far the cheapest option, but make sure you refer to your pump’s schematics to determine if the diffuser needs replacing as well.
  • Replace whole pool pump with the correct match
  • If the new pump is a dual or variable speed, run only on the lower speeds.
Click Here to View Replacement Pump Parts

Click Here to View Replacement Pumps 
 

Step 6

Closed Diverter Valves - If you have any diverter valves after the pump and filter, make sure they are completely open for max water flow. A partially closed diverter valve will throttle water flow, creating a flow bottleneck

Click Here to View Replacement Diverter Valves

Step 7

Enlarge Return Jets - One manufacturer has suggested replacing the return jets with ones with larger exit holes. This won't be as effective a change as something like changing your pump's impeller, but it should help.

Click Here to View Common Return Jets

Step 8

The key to eliminating high pressure in your pool filter system is reviewing potential flow restrictors or blockages in your system. 

Clean Your Filter - If you have diverter valves after the pump, you may have inadvertently closed off a section of your return lines. This action will restrict the total return flow and cause back pressure in your system. Open up these return lines.

Comments

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(81 to 120 of 194)

 Posted: 6/27/2017 

Hi - first of all, thank you for all these answers, what a great resource! I am having a problem I can't figure out. I cleaned my cartridge filter recently and, as expected, the pressure on the gauge went from close to 20 down to about 12, which is what it always does. However, instead of the normal improvement in water pressure coming out of the jet, the water is just BLASTING out. But the gauge still reads around 12, so the overall pressure is not high. I can't even hook up my vacuum - it never "catches" suction. Do I have an air leak somewhere? Where could it be? It just seems odd that the pressure is not high at the gauge, too. Thanks in advance!
 Reply

InyoPools Product Specialist  Posted: 6/27/2017 

Yassr - I would guess that sunscreen oils and chemicals have built up into the folds of the filter (assuming they are cartridge filters) which is starting to reduce the flow through the filter. Try cleaning the filters with a solution of TSP.
 Reply

 Posted: 6/26/2017 

Hello . I have a pool of 8 filters that was operating probably for 2 years normally , but suddenly pressure go higher over 20 psi whenever i try to turn 5 filters or more pressure gos higher over 20 psi
Q.what my is happening?

 Reply

InyoPools Product Specialist  Posted: 6/26/2017 

db - I assume that your return hose is the AG hose from your filter to the pool that returns water to the pool. If you have upgraded your pump's HP significantly, the regular return hose may not be designed to handle the added pressure. If you can't get a heavier hose, you might consider plumbing the return line with PVC pipe.
 Reply

 Posted: 6/25/2017 

You are awesome...
 Reply

 Posted: 6/24/2017 

My return hose spings leaks like a sprinkler . I have replaced it four times. Brand new Hayward pump and sand filter operating at 18psi. Thanks for any suggestions
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InyoPools Product Specialist  Posted: 6/19/2017 

Pam - It takes a lot of pressure to blow a hole in a PVC pipe. Did you have any indication of extremely high pressure? How large is your pump? if you have a 2 or 3 HP pump on an 1 1/2" piping system, you might have created pressures your system could not take. Or, your piping may have been damaged in storage or during installation if the weather was cold and the pipe were thrown around and developed invisible fractures. Did you use Schedule 40 piping?
 Reply

 Posted: 6/19/2017 

I have a sand filter and pool was installed two years ago. I just turned on my pump and it blew a hole in the pvc pipe. Why would this happen?
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InyoPools Product Specialist  Posted: 6/17/2017 

martha - When you say 'cartridge", do you mean the whole grid assembly in your DE filter and that you replaced the grid assembly? If so, you may have too much DE powder in your filter that's blocking water flow. Try backwashing your filter again and then only adding 80% of the powder to recharge it.
 Reply

 Posted: 6/15/2017 

Have a hayward de filter that we just replaced the cartride since it was torn and now the pressure is building up after a few minutes and stopping the flow of water. The cartridge is not dirty and does not need to be backwashed...When we take the cartridge out and run it the pressure is fine...Any ideas?
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InyoPools Product Specialist  Posted: 6/12/2017 

Not pool happy - It sounds like you may have low water pressure and don't have enough pressure to supply all your jets. See our guide on "How to Correct Low Water Pressure in Your Pool System". Check for a clogged impeller first.
 Reply

 Posted: 6/10/2017 

OK, so I am searching for answers, and have not found any! last fall I blew out all my lines and no problems.I stated up my pool and my sand filter pressure is runing at aboutv 18 psi. My step returns are fine, but my two side jets are putting out almost nothing. I changed my filter's sand just now. No air leaks I can see. If I put a hose in one jet, water comes out the other jet when my step valve is off, with pump not running. Also if I plug one jet with the hose running in the other, and undo the disconnect just after the the filter, water comes out of it. How come I cant fnd the answer to my problem?
 Reply

InyoPools Product Specialist  Posted: 6/9/2017 

nonna - You may have air pressure building up in the top of your filter tank due to suction air leaks. See our guide on "How to Identify and Correct Air Leaks". Check first any connections before the pump that you may have disconnected when you changed the filter sand.
 Reply

InyoPools Product Specialist  Posted: 6/8/2017 

Jana - To my knowledge, there is no pipe installed in a pool system designed to pop apart when the pressure builds up. I would guess that whoever installed your system forgot to glue that connection.
 Reply

 Posted: 6/7/2017 

we replaced our sand in the TR60 Triton, but the pressure rises from 10 to 20 within a couple of hours running the filter. Any suggestions on what may be the culprit? thanks!
 Reply

 Posted: 6/6/2017 

I have a Hayward DE filtered around 20,000 gal pool. I am having a problem and lack the knowledge and need info. Is there a hard plumbed pipe that is supposed to be installed to prevent pressure valve from blowing. I have a pipe that keeps popping apart after filter runs for a little while. Thank you so much for any help.
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InyoPools Product Specialist  Posted: 6/4/2017 

Luis - First, you may have too much DE Powder in your filter. Backwash the filter again and then only recharge with 80% of the suggested load. Second, you may have backpressure building up in the top of your DE filter tank due to a suction air leak in the piping between your pump and the skimmer. A good indication of this is a strong blowback through the pump to the pool when you shut off the pump. If you filter has an air release tube down the center of the tank, make sure the tube and screen cap at the top are clear. To resolve your suction leak, see our guide on "How to Identify and Correct Air Leaks".
 Reply

InyoPools Product Specialist  Posted: 6/4/2017 

Andy - You may have backpressure building up in your filter tank. See Step 3, Suction Air Leak, and Step 4, Clogged Breather Tube, in this guide.
 Reply

 Posted: 6/3/2017 

Have a pentair DE filter; I cleaned the filter completely psi 8-10; vacuum the pool but after a few hours the pressure went up to 25. I backwashed but again a couple hrs it went back up. Any suggestions on what could be the cause. I never had this problem before and have no clue what else to do.
 Reply

 Posted: 6/2/2017 

I just purchased a Hayward Xstream. Runs great for a few hours but then pressure goes up. Removed cartridge, clean it and same thing. I can't get more than 2-3 hours before this keeps happening.
 Reply

InyoPools Product Specialist  Posted: 5/30/2017 

Dawn - If your system has high pressure, try opening up the relief valve at the top of your filter. If air comes out and your pressure drops, you have back pressure building up in the top of your filter tank. To correct his, see our guide on "How to Identify and Correct Air Leaks".
 Reply

InyoPools Product Specialist  Posted: 5/30/2017 

paul - 150 sq. ft. is the upper-end filter for a 1 HP pump and the lower end for a 1.5 HP pump. Most dealers suggest getting a filter that is 25% larger than what you need for a high water pressure buffer and for the convenience of not having to clean it as often. If I understand you correctly and you have bought three replacement filters in the last four years, it's a good indication that the filter is too small for the pump.
 Reply

 Posted: 5/30/2017 

I'm having an issue with DE streaming back into the pool only during vacuuming. On intial startup, I have no problems with the DE staying in the filter however 1 minute after starting to vacuum, it starts backstreaming. I checked the plates and the fingers and they all look fine. The filter is a HEYWARD EC50. Anyone else have this issue?
 Reply

 Posted: 5/29/2017 

How do I purge the motor to release any air?
 Reply

 Posted: 5/29/2017 

I am having a problem with high filter pressure, normal pressure should be around 8-10 psi, it goes up to 25 psi. Pump and filter is a Advantage 1.5 (56 frame) 150 sq f.t. cartridge filter pack-spl.556. I have checked everything, and even bought three new fiters in the past four years. I have talked to pool service people they said to get a larger filter, my system is sized correctly. Any suggestions.
 Reply

InyoPools Product Specialist  Posted: 5/25/2017 

coreytk - You may have backpressure building up in the top of your sand filter tank due to a suction air leak in the piping between your pump and the skimmer. A good indication of this is a strong blowback through the pump to the pool when you shut off the pump. If you filter has an air release tube down the center of the tank, make sure the tube and screen cap at the top are clear. To resolve your suction leak, see our guide on "How to Identify and Correct Air Leaks".
 Reply

 Posted: 5/23/2017 

I opened my pool a few days ago after replacing the sand and changing all O-rings and gaskets. Hooked everything up, backwashed and rinsed, then moved to filter. All was operating as it should. A couple of hours later, water was coming out where the multi-port valve assembly meets the sand filter. I killed the power, took the multi-port assembly off, re-lubed the O-ring, then put it back on and tightened it back down, good to go. After a few hours, same thing happened. I removed a little of the sand with my Shop Vac, this seemed to help as it went 6-7 hours before the problem came back.

I tore it down again yesterday, checked all the fittings and hoses for any blockages. No water seeping out from any of the unions. Took out a little more sand, maybe 5 lbs or so. Fired it up, it ran fine for about 6 hours or so, but he pressure had went up by 5-6 psi. It seems as if the pressure keeps steadily rising the longer the pump runs.

I have an Ecco 22" sand filter, #250 lbs of #20 silica sand, Waterway 1.5 hp pump.

Any suggestions?

 Reply

InyoPools Product Specialist  Posted: 5/22/2017 

Dawn - You may have too much DE powder in your filter. Try backwashing the filter and then adding only 80% of the recommended amount. When you backwash, only 80% of the power is removed. Only add the full amount after disassembling the grid assembly and rinsing out all the DE powder.
 Reply

InyoPools Product Specialist  Posted: 5/22/2017 

Angelo - You may have a suction air leak before the pump that is causing air pressure to collect in the top of your filter tank and causing back pressure. This would be noticeable when you turn off your pump and hear a surge of water back through the pump into the skimmer. See our guide on "How to Identify and Correct Air Leaks". Also, just to cover the bases, check that your impeller is not clogged. See our guide on "How To Clean Out a Pool Pump Impeller".
 Reply

 Posted: 5/21/2017 

I just replaced my sand filter with a DE. I've added the recommended powder. My pressure starts out at 10psi. In 2 minutes it is up to 20psi and barely pushing water into the pool. Any suggestions or thought?
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 Posted: 5/19/2017 

The water flow coming into the pool looses pressure shortly after starting the pump. The pressure gauche reads around 10-12 psi when I start it but slowly rises a bit and the water flow into the pool decreases significamtly. Ideas?
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InyoPools Product Specialist  Posted: 5/6/2017 

JustGalee - More than likely, your pump was too strong for your filter. You were trying to move more water through your filter than the filter was designed to handle. The filter should be sized to handle 20% more GPM than the pump can generate. Or, the filter was operating at a very high pressure because the filter had not been cleaned for a long period of time or the return lines were blocked.
 Reply

InyoPools Product Specialist  Posted: 5/6/2017 

Bone - You may have too much DE power in your filter. When you backwash, about 20% of the power is left. Try recharging with only 80% of a standard load. Also, check that the breather tube, from the top of the tank to the bottom, is not blocked. And, if you haven’t cleaned your filter grids for a while, I would pull the grid assembly apart and clean the individual grids thoroughly.
 Reply

 Posted: 5/4/2017 

I have a Pentair Triton II sand filter that just exploded! I have had it for a few years and I'm not sure why it decided to blow a 1 1/2-2 ft slit in the side. It will have to be replaced but what would cause it to explode like that??
 Reply

 Posted: 5/4/2017 

I opened the pool myself this year. Did everything I was supposed to do and for the first day, the pressure was around 10-12 (as usual) with good water flow. The pressure then jumped up to 20 and has stayed there with decreased water flow. There is plenty of water coming in from suction side. Only time it drops is if I put the waterfall on or turn off the water to it. Water level is good, reapplied Teflon tape to chlorinator points, checked seals on pump lid, checked impeller and cleaned the DE grid (closers didn't). Am I missing something?
 Reply

Anonymous  Posted: 5/3/2017 

RHP997 - You may have too much media in your filter. When you replenish the media after backwashing, only add about 80% of the suggested initial load amount. 20% is still in the filter. Also, if your water flow is dwindling over time. you may have air pressure building up in the top of your filter that is creating backpressure. You may see a backward surge to the skimmer when you shut off the pump. This is caused by a suction leak in the fittings before and at the pump. See our guide on "How to Identify and Correct Air Leaks".
 Reply

InyoPools Product Specialist  Posted: 5/2/2017 

anj109 - If you haven't changed your sand in the last 5 years, I would replace it now. If your filter has a breather tube from the tank top to its bottom, check that that is clear. Also, check for blockages in the return pipes after the filter. Make sure you haven't inadvertently closed off a diverter valve in the returns lines that was opened before.
 Reply

 Posted: 5/2/2017 

With fresh grids and the correct amount of media my pressure never is below 22psi. After the filter runs for about an hour the filter basket is only half full and the pressure is over 35psi. This is getting so old!! Runtime keeps dwindling over time, I use to get 5 to 6 hrs and now it's under an hour. I can't even keep my pool clear constantly having to play filter-sitter!! Help
2hp 2" fns60

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 Posted: 4/30/2017 

My pressure in my filter was about 22 psi last year. I just opened the pool up and it's hovering around 44 psi now. I've backwashed twice and still not lower. Any ideas? Thanks!
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InyoPools Product Specialist  Posted: 4/25/2017 

Joey - Not sure this is a problem. What do you mean by "over fill the tank"? This is a closed system so when gravity fills up the tank you don't lose any water. At worse, it may flow out the tank back to the pool until it reaches equilibrium. This is normal when the pump is off.
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