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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.

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(121 to 160 of 194)

 Posted: 4/24/2017 

I have Hayward Xtreme Cartridge filter 100sq with 1.0 HP, just instead for above ground, the problem Is : water keeps flowing from skimmer to pump to and over fill the tank even when it's shut off.
 Reply

InyoPools Product Specialist  Posted: 4/18/2017 

Hans - 17 psi is not necessarily a high value for water pressure. Many systems operate fine at this level. If your system was operating at 10 and went up to 17 you might be starting to have a problem but I wouldn't worry about high pressure until you get in the high 20's.
 Reply

 Posted: 4/17/2017 

Your video is great but it only addresses cartridge filters. I have a sand filter that even when I backwash my new pressure is at 17 psi. I've changed the sand I've changed the filters. There is great flow in the pool and the pool pump is about two years old. I've got about a 28,000 gallon pool with a 1.5 hp pump. Not quite sure what else to do. Thought maybe to change gauge out on sand filter as another option before going in on anything else.
 Reply

InyoPools Product Specialist  Posted: 11/18/2016 

htij - To downsize to an equivalent 1 HP up rated Sta-Rite Max-E Pro pump from your 1 1/2 HP up rated pump (P6RA6F-206L), you would need to replace your impeller with the 1 HP impeller, C105-238P.
 Reply

 Posted: 11/16/2016 

At the suggestion of a local pool store I went from a 1hp to 1.5hp based on the fact that the pool has an in floor cleaning system. I'm new to the house and thought the previous owner had skimped on the pump. The pressure now runs at 20-28PSI as it moves through the zones. It's a STA-RITE MAX-E-PRO P6RA6F-206L. I see your suggestion on down sizing the impeller. What impeller should I down size to? Note that I took the gear assembly out of the in floor cleaning system and it still runs at about 12PSI.
 Reply

InyoPools Product Specialist  Posted: 10/31/2016 

Mpn - These energy filters generally operate at ;higher pressure than the regular pool filters - like 30 psi. But if you are running at 45-55, you might look at replacing the energy filter cartridge.
 Reply

 Posted: 10/29/2016 

I have a energy filter on my system which had a high pressure over 35 fir the last two weeks and is increasing but nothing has Chang ed regarding the valves or pump filters etc. pump filter gauge reads at 15 psi but the little energy filter reads 45-55psi. What is wrong and how to address it please?
 Reply

 Posted: 10/15/2016 

That's what was driving me crazy. Nothing was leaking anywhere. You would think with all the pressure from the pump on those O Rings, something should have been leaking, but it was completely dry. Oh well, I guess you have to get lucky once every 100 years. Thx
 Reply

InyoPools Product Specialist  Posted: 10/11/2016 

Rick - Sorry for the late response - system issues. But congratulations on you success. This is confusing to me. It did sound like your problem was due to a suction air leak - back-pressure building up in the top of the tank and blowing out backwards thru the pump when the pump was shut off. The couplings you tightened were on the pressure side of the pump where water would squirt out of a leak rather than air sucking in. Did you see any water squirting out at these couplings when the pump was on? I'll have to work on this some more to see if there is some kind of pressure-suction relationship that caused your problem. Congratulations again. You are a great detective.
 Reply

 Posted: 10/6/2016 

I finally figured it out. Everybody I spoke with were convinced that it was a suction leak. I replaced the o rings on the filter basket, drain port on the strainer basket and pump, the couplings on the inlet and outlet of the pump and on the Jandy valve. I also disconnected the MX8 cleaner thinking on of the hose couplings could be leaking. Nothing worked. I finally looked at the two couplings between the backwash valve and the sand filter. I tightened them about 1/8 to 1/4 each and WOW, that did it. Works great now. Thanks for all your help.
 Reply

 Posted: 9/27/2016 

I know there isn't any air coming out the bleed port by the gauge. I'll have to take the tank apart and check on the one inside. I assume you're talking about the one with the little filter attached. Thx
 Reply

InyoPools Product Specialist  Posted: 9/20/2016 

Rick - Your system may be building up back pressure in the top of your filter tank. There is an air bleed tube going up the center of your tank. Check to see if that tube is clogged.
 Reply

 Posted: 9/18/2016 

I have a Sta Rte System 3 with a Sta Rite 1 1/2 HP pump. The filter is running at 15 psi and I flush it when it gets to 17-18 psi. It has been running for years this way. All of a sudden, I have a problem with the water blowing back through the basket and blowing the lid off it. I have back washed the filter and it still does it running at 15 psi. I can't figure it out since it has run for years this way just fine. Please Help.
 Reply

InyoPools Product Specialist  Posted: 9/10/2016 

Juny - I need more information. Is the water spewing out the top of the filter or the pump. If the filter, is it flowing out from the multiport valve on a sand filter, or for the joint between the two halves of a cartridge filter?
 Reply

 Posted: 9/7/2016 

I A Hayward pool pump and it is spewing water out of the top,it runs after I turn it on it runs a
few minutes and then the pressure starts rising (to around 20 PSI) and then it starts spewing water out of the sealed top,when I turn the pump off and remove the lid the filter is stuck on the inside of the lid I have to pull it off any ideas what to do I already replace the O-ring as I thought that was a problem
 Reply

InyoPools Product Specialist  Posted: 8/1/2016 

Kudipi - I'd clean the top of the tube good and then blow through the tube to see if it is clear. Or place a clean plastic bag with a hole in it over the top of the tube to blow through it. If you can figure out a way to attach a hose to the tube, that would work too.
 Reply

 Posted: 7/31/2016 

Having high pressure... saw several places to check for clogs in breather tube but nowhere did I see how to check this (it is dark in there!) or how to try to unblock this if it is clogged.. saw someone posting they stuck a hanger wire in there but might this not just jam a blockage in farther? Can I try to blow out a possible blockage with a hose sprayer attachment?
 Reply

InyoPools Product Specialist  Posted: 7/11/2016 

stan - Try blowing down the tube to make sure you have a clear path to the bottom of the tank. Then check for suction air leaks between the pump and the pool to see if air is getting into the system. The problem may be with the cartridge. A "clean" cartridge may be clogged with oils and chemicals. Try soaking the cartridge overnight in a TSP solution.
 Reply

InyoPools Product Specialist  Posted: 7/8/2016 

TJ - Try shocking the pool again. Then backwash and rinse your filter 2-3 time to clear any contaminants out of the sand.
 Reply

 Posted: 7/7/2016 

Correction from earlier post, The filter is model Hayward number 9002, the pump model i cannot make out from the plate but is says max flo 1hp on the motor. It does have a breather tube in the middle of the filter which i stuck a wire hanger down and no clogs appeared to be there. I changed filters yesterday and the system ran at 16psi again for 5 hours, then crept up to 21 again. What should i look at and check next?
 Reply

 Posted: 7/5/2016 

I HAVE AN INGROUND POOL, 14 YEARS OLD, THAT WAS DOWN FOR ABOUT 8 MONTHS WITH NO FLOW DUE TO A MOTHERBOARD AND MULTIPORT VALVE FAILURE; AFTER REPLACING THE MOTHERBOARD AND VALVE, I REMOVED SAND AND INSPECTED LATERALS AND FOUND AND REPLACE 4 CRACKED ONES. I REPLACE SAND SINCE I WAS THERE AND CHECK FOR ANY OTHER CONCERNS WHICH I SAW NONE. I SHOCKED THE POOL, ADDED SALT AND RAN FILTER FOR 24 HOURS. THE WATER SEEMS TO BE CLEAN AND BLUE BUT REMAINS CLOUDY AND MY PRESSURE AT THE TANK ROSE BACK TO 20 - 21 PSI AFTER FILTERING FOR 24 HOURS. I AM AT A LOSS TO WHAT I COULD BE MISSING.......ANY IDEAS ???
 Reply

InyoPools Product Specialist  Posted: 7/1/2016 

wayne - I'm not sure what's going on here. A 22" sand filter is more than adequate for a 1 HP pump. Check the specs on your pump. It sounds like you have a much larger pump. Try setting the filter valve to recirculate. If you get the same strong return with the filter valve in recirculate, you know the filter is not the issue. Do you have an AG pool pump? A pump's real HP is the product of the listed HP times its Service Factor (SF) - see motor's label. Is your real HP much greater than 1.0 HP?
 Reply

 Posted: 6/30/2016 

I have a 24 ft round above ground.Ive had it for 10 yrs.It has a 22 inch sand filter with a 1 hp pump.All of a sudden it blew a hole in the side of the sand tank.I patched it,turned it on,and it blew the patch out.The problem is not bad sand but when I put my hand in front of the return line inside the pool, it blows my hand away.All of a sudden its putting out so much pressure you cant keep your hand there.I have not changed anything on the pump,but I did change my sand about 7 mos ago.Why the sudden increase in out put.
Thanks
 Reply

InyoPools Product Specialist  Posted: 6/24/2016 

stan - I couldn't identify your filter with the description "Hayward 9001 cartridge filter'. Check to see if your filter has a breather tube running from top to bottom inside your tank. If this tube is clogged, you may have air pressure building up inside your take creating back pressure.
 Reply

 Posted: 6/23/2016 

I have a Hayward 9001 cartridge filter, Hayward 1.0 HP pump and Hayward in line chlorinator. I have a 15x30 oval pool 54 inch. It is hard plumbed with 1 1/2 inch pipe ten feet away. i have no shut off valves on it. I noticed one day that the filter pressure was at 25 and the return flow was not as strong. I changed cartridge filter with a spare. The system ran all day at 16 psi and return was strong. The next day the pressure steadily increased back over 22 psi. what seems to be going on and what pressure should it be?
 Reply

InyoPools Product Specialist  Posted: 6/20/2016 

Cliff44 - Yes, you can run the filter without the cartridge to see if that reduces your psi. But if your initial psi was 20 with a clean filter, that is probably your operating psi. If you ran your green slime through the filter, you may have to spend more time getting the slime out of the folds of the cartridge. If you have a breather tube going up the center of the filter tank, make sure that tube is not clogged. Finally, some of the pool debris may have clogged your pump’s impeller. See our guide on "How To Clean Out a Pool Pump Impeller" for instructions on checking your pump's impeller.
 Reply

InyoPools Product Specialist  Posted: 6/17/2016 

James - Generally when you are first opening your pool, the cartridge filter will get clogged and have to be rinsed off several times until the pools residue is filtered out. Keep at it for a week and you should get back to a normal cleaning cycle.
 Reply

 Posted: 6/17/2016 

I have a 28 ft round above ground pool and just installed a new Hayward 1.5 pump with cartridge filter system, my pool was extremely green, swamp green actually but after 3 days it is now light green. My question is, from the initial start my psi was close to 20 and even after I clean the filter and reinstall the psi is 20. Can I operate the system without the filter just to see if that is the problem? I don't see any air leaks in the hose or any air in the top of the skimmer on the pump so I'm just not sure what else to do. I know the pool was dirty but even after a thorough filter cleaning you can barely feel the water returning back to the pool after 30 min. Any help would be appreciated.
 Reply

Anonymous  Posted: 6/16/2016 

Did u check the top and bottom manifolds to see if they were cracked. Also check ban that u tightened back up
 Reply

 Posted: 6/14/2016 

I just replaced my older de filter for a brand new cartridge filter I'm using a 1 hp pump with it, pump is only 1/2 season old. Pool hasn't been fully opened yet I just got all the green out of the water before switching to the new filter. Ran filter for 1-2 days and the pressure has risen to 20psi. I took the cartridge out and just rinsed it with the garden hose and the pressure would go back to 15 psi, but it rises back to 20 within an hour or so. Is there something more I should be doing, I was hoping switching to a cart filter would be a little less maintenance. Btw filter is a Hayward xstream 100sq in. filter and pool is 21' round 52" deep.
Thanks in advance
James
 Reply

InyoPools Product Specialist  Posted: 6/13/2016 

Lou - If your filter has a breather tube from the top of the tank to the bottom, check to see if that tube is blocked. A blocked tube could be causing back pressure in the top of your tank. If you have a sand filter, change the sand and check the laterals, lateral hub and standpipe for cracks. Sand may be building up in the laterals blocking flow during filtration.
 Reply

 Posted: 6/11/2016 

I just opened my pool and after a couple minutes the pressure builds up and you see the flow drop at the returns. I back wash it and it's good for a couple minutes then same problem .
 Reply

InyoPools Product Specialist  Posted: 6/7/2016 

Bethany - Did you remember to turn the pump off each time you rotated the handle to change filter modes? If not, the spider gasket in the Multiport Valve is probably blown. It's not a big deal to fix. See our guide on "How to Correct Low Water Pressure in Your Pool System".
 Reply

 Posted: 6/7/2016 

I just installed a new waterway top mount sand filter for in ground pool. We have massive leak at the top where valve sits on the filter. We have removed this made sure it was on correctly, used silicone, checked o ring and still leaks. It does not leak on waste that bypasses the filter, I even got it to backwash thru the filter but then tried to go rinse or filter and you can see that there is pressure built up and then water just pores out. Now the day we installed it we had no issues. But then as we begin to turn multi port valve to backwash etc. We started having issues. This is brand new. I do not know what else to do.
 Reply

InyoPools Product Specialist  Posted: 6/3/2016 

Pam - See if your pool water flow improves if you run the filter in recirculate mode, bypassing the filter. If it does, you may need to replace your filter. Sometimes they look clean, but with use, oils and chemical build up in the folds that are difficult to get out. Also, check to make sure your pump's impeller is not clogged. For more information, see our blog on "Correcting Low Water Pressure".
 Reply

 Posted: 6/2/2016 

I have a 35,000 gallon pool with a PCC 2000 cleaning system, a 1.5 HP pump, a hot tub, and a cartridge filter. Pool is about 18 years old. Experiencing lack of suction. Pool is filtering but at a very slow rate (can particularly tell when vacuuming). Pressure has ranged between 22 and over 25 since opening it two weeks ago. Skimmer lid occasionally pops off. Replaced all the o-rings, fed a bladder and hose into all returns to the pump and did seem to loosen up a little debris and perhaps an air bubble, but pool still not filtering well. Hot tub making an odd sound (almost a groaning sound). I have just a slight bit of water running to the hot tub to get it to slowly overflow to the pool. Worried I may still have a clog in a line, an air leak or a collapsed line. Is there any other way to diagnose this?
 Reply

InyoPools Product Specialist  Posted: 5/31/2016 

mf2593 - I assume you have a Hayward Perflex DE Filter. According to the User's Manual, "If the concentration of minerals is allowed to get too high, the minerals will form deposits on the Flex-Tubes inside the filter, and will eventually result in shortened filter cycles. To guard against this, a yearly chemical cleaning (soaking) of the Flex-Tube assembly is suggested". If the tubes have not been soaked yearly or the poll chemistry has not been maintained, the Flex-Tubes may be to the point where they can't be soaked clean. You might have to replace the assembly. See what Hayward says at 866-772-2100.
 Reply

InyoPools Product Specialist  Posted: 5/31/2016 

rogos - First your filter may be too small for a 1.5 hp pump. Also, something may be wrong with the Posi-Loc ring or tank. Check that the joints on the Posi-Loc ring are working and that there is no damage on the tank where the ring attaches.
 Reply

InyoPools Product Specialist  Posted: 5/30/2016 

vic - If your filter has a breather tube going up the center of your filter top to bottom, check to make sure it and the screen cap are not clogged. If it is clogged, you may have air building up in the top of the tank causing backpressure. Also, if you haven’t replaced your filter grids in a while, you might consider replacing them. They may look clean, but oil and chemical may be clogging the fabric.
 Reply

InyoPools Product Specialist  Posted: 5/30/2016 

Mo – If your 1.5 HP Super pump is too strong, I would suggest reducing the pump’s impeller size. This would effectively change your pump to 1 HP. For detailed instructions, see our guide on “How to Downsize a Pool Pump Impeller”.
 Reply