A weak pool jet is one of the most frequent problems for pool owners. If you ask a pool professional “Why are my pool jets not working?”, you may receive a blank stare and a pause. This reaction is due to the fact that we know the solution could be simple, but narrowing it down is time-consuming. We’ll separate the cause of low pool jet pressure into two parts. This will hopefully save you time from reading a section that doesn’t pertain to your situation. Part I will discuss low jet pressure when the filter gauge has a low PSI reading. In Part II we’ll discuss low jet pressure when the filter gauge has a high PSI reading.
Part I Weak Jets and Low PSI
Some of you may be wondering what would be considered a low PSI. Anything lower than your normal operating PSI is considered low. For example, let’s say your normal operating PSI is 10-15. If your gauge is reading 5 PSI, it’s low. This would result in the pool jets not being as strong as expected. Unless you’ve recently lowered the horsepower or RPMs of the pump, low jet pressure is a problem and it needs to be corrected.
The Obvious but Overlooked
The water level of your pool should be checked first. It needs to be at least halfway up the skimmer door’s opening. A low water level can cause a pump to take in air. This will not only decrease flow, but it will cause the pump to run dry and burn up.
Empty the skimmer basket and pump basket of any debris. This should be part of the regular pool maintenance, but it’s a simple task that is often overlooked. A clogged basket can cause the pump to work harder as it tries to circulate the water. Again, this can result in damage to the pump.
Air Is the Enemy
The most common reason for weak jets is an air leak. An air leak would come from the suction side of the system. This would be the area between the skimmer and the pump. One way to determine if you have an air leak is by looking for air bubbles coming out of the return jets. Another sign is air in the pump strainer. The pump strainer, in most cases, should be full of water and have no visible air.
Pump lid O-rings are a habitual offender of air leaks. The O-ring can expand or deteriorate over time and allow air to enter the pump. You can try applying a silicone or Teflon lubricant to see if it helps, but often times it needs to be replaced.
Plumbing fittings will also draw air. A popular technician trick is to use burning incense. While the pump is running, wave the burning incense near suspected areas. The smoke will be drawn in, if there is a leak. Check the fitting on the pump intake, the couplings and elbows. Cut out and replace any fittings that have an air leak.
Valves can be inspected like the plumbing fittings. Diverter valves will usually have internal O-rings. These O-rings can easily be replaced to fix an air leak. Simple ball valves are not usually repairable and need to be replaced, if there is a leak.
Drain plugs are found on most pumps. These plugs are usually used to drain the pump when a pool is winterized. They should be tightened firmly into the pump. Inspect the drain plug and drain plug O-ring. Replace them if they look decrepit.
Pump Problems
Pool owners often tell us that the pool pump pressure is too low. With low jet pressure, the cause could be a damaged or clogged impeller. The pump will need to be split in half in order to inspect the impeller. Dog hair, pine needles and other small debris are main culprits for a clogged impeller. Replace the impeller if the body or any of the veins are cracked.
If the pump strainer is not full of water and an air leak has been ruled out, your pump may not be fully primed. With the pump off, remove the lid and fill the strainer with water. Keep the water running for a couple minutes. This will allow the pipes to fill with water. If you turn on the pump and it still struggles to prime, it could be an issue with the suction-side plumbing. Check out our article titled “How To: Fix Priming Problems In Your Pool Plumbing” for an in-depth look at priming problems.
Plumbing Issues
There may be a clogged suction side line if very little or no water is entering the pump. This will often occur if a leaf trap or vac plate is not used when vacuuming the pool. The clog will occur between the skimmer or vacuum port and the pump. A traditional plumbing snake will not usually work on pool plumbing, because of all the 90° turns. We recommend using an electrician’s fish tape or a drain cleaning water bladder. 
Part II Weak Jets and High PSI
What is a high PSI? The general rule is that 10 PSI above the normal operating pressure is considered high. A high PSI reading should be addressed quickly. Damage to the filter, pump and plumbing can occur if high PSI is sustained.
The Primary Suspect
The predominant factor for high PSI and low flow is a dirty filter. Cleaning the filter will normally lower the PSI and improve jet flow. In order to clean, sand and DE filters need to be backwashed and cartridge elements need to be hosed down. DE grids and cartridges can be soaked in a filter cleaner to remove oils and grease that aren’t removed during normal cleaning. If the PSI remains high after cleaning the filter, the filter media may need to be replaced. By media, we mean the sand, DE grids or cartridges.
The Swamp Effect
Green Pool ✓ Cloudy Pool✓ No Flow✓ Customers frequently tell us that they clean the filter and 20 minutes later the PSI is high and the flow is poor. Then we ask, “Can you see the bottom of the pool?” and “No” is the consistent response. The reason the PSI is jumping up is because the filter is catching all that extra debris. The first step is killing the algae. The pool usually clouds up after this. The filter will need to be cleaned several times a day until the water is clear. The PSI should normalize once the water is looking good.
Note: If the reading on the pressure gauge does not drop when the pump shuts off, it may be a bad gauge. The pressure gauge is inexpensive and very easy to replace.
We addressed the most popular causes of pool jets not working. If you have any further questions regarding weak pool jets, visit us over at INYOpools.com. Please leave a comment and let us know what corrected your pool pressure issue.
Having an issue with my pool jets. First of all I have a new pump motor, new switch and new spa control. At first the jets worked fine. Switch on/off ok. Now after not turning on for several hours if you push the switch nothing happens. But if you pull the switch out and stretch the hose then push the switch it works. I also suctioned the water out of the pvc pipe that holds the tubing.
New to the pool world. New sand filter and jet was working great PSI was normal. I tried to connect an automatic pool cleaner to the skimmer vac and since then the flow on my jet is very weak. Water in the sand glass is clear and skimmer basket is free of debris. I never could figure out how to get the brand new automatic pool cleaner to work – worked for about 10 minutes then quit plus my jet is weak now. What could have caused this?
Hello Susie – The pump may not be getting enough water when you connect the pool cleaner. You can try opening the main drain line so that the pump can get more water. The key is to just slightly open the main drain because opening it too far can cause the cleaner to get stuck on the drain. Also, keep an eye on the filter gauge. If the pressure rises 10 psi above the normal pressure, it’s time to backwash the filter.
I have a new Pentair Superflo. It runs great for a few days and then the flow from the jet starts to drop. After a couple of days it goes down to almost nothing. All I have to do is turn off the power to the pump and immediately turn it right back on and the flow from the jet returns to enormous amount.
Thanks guys.
Hey guys, just opening my pool and as well my return jet is weak, so yesterday I did a big backwash and boom it was working like a champ for at least 4 hours till I went to bed. Then this morning I woke up and it was weak again?? No air bubbles in the pump and I just changed the sand in my filter last week. I’m a little lost because we also replaced at the connections and hoses and I did check for leaks and there are none.
Hello Steve – Is the pool cloudy? Try backwashing the filter again.
Yes was greenish cause I was just starting it up. Did my shock treatment then had the water analyzed. Yesterday did my backwash and added the needed chemicals and this morning it’s blue And still somewhat cloudy.
The likely cause of your weak jets is a filter that is filling up with debris. You may have to backwash a couple of times a day until the water clears up.
Great thanks for the quick response. I’m new to this pool thing. Should I back wash a lot or just a bit each time?
I’d backwash until the water starts to look clear in the sight glass.
When the filter is on recirculate…pressure from jets is strong…when I turn it to filter…pressure from jets is weak and psi is very high. Backwashing temporarily fixes it but only for a few minutes. I have a Hayward de4800 filter that’s about 15-17 years old…there are tiny bubbles in the pump window…when the pump shuts off…the water level will drop in the pump strainer basket…PSI reaches 25-30 after 10-15 minutes. Thoughts?
Hello Tim – It sounds like you have a couple issues. The air in the pump strainer is the result of an air leak. We address air leaks in the “Air Is The Enemy” section in the article above. The filter issue is discussed in Part II of this article.
Hello! Just opened my pool for
The year after having my liner replaced
I’m dealing with low pressure
In my returns but not in the system as a whole. I have 6 returns. Two of the 6 are receiving adequate pressure. As you move around to the other returns the pressure becomes less and less with hardly feeling it at all once you’ve reached the 6th return. My pump becomes fully primed with zero bubbles. The returns themselves have some bubbles at start up but eventually go away. My pressures is running the normal range. I’ve fixed a few leaks but it’s on the pressure side which helped increase flow oddly enough. My water level is good, my pump basket o-ring is good, I’ve backwashed, I’ve replaced the Paramount floor cleaner dome O-ring, made sure my skimmer basket and pump basket are cleaned out. The only thing I haven’t checked is the inlet union o-ring
To the pump but since I have no air bubbles I don’t see a reason to unscrew the union to check. I was going
To blow the lines but haven’t yet since I have a little bit of flow. At a total loss for what else could be causing
The problem if I don’t have air
In my pump. Any suggestions would be greatly appreciated.
Hello Jordan – Maybe the pressure gauge isn’t giving a correct reading. If you have a sand or DE filter, set the valve on recirculate and run the pump. If you have a cartridge filter, take the cartridge out and put the lid back on the filter. Run the pump without the cartridge. Do all of the jets start to work?
That’s good to know that a regular plumbing snake might not work for a pool drain. I have a regular one so that I can fix the sink when it gets clogged, but I wouldn’t want to have to buy a new one just for the pool, since it, doesn’t clog very often. I’ll have to take a look for a repairman in my area who could take care of it for me.
I just recently purchased a replacement new 2HP Pool Motor (the same HP of my previous motor) for my inground Pool. However, each time the pump runs, I am losing 1-2 inches of water? I have placed a 5-gallon bucket in the pool to test the water loss. And, sure enough, the bucket water remains at the same level, but, not the Pool water level. I have (1) Skimmer & (2) return jets, which are circulating when pump is on, however, I still have water loss. I thought the return jets were meant to return the clean water back into the pool? Please advise!!
Hello Debbie – We’d be glad to assist you. If you are not noticing any leaks by the equipment, I would start looking at other common leak spots. This would include the skimmer, light niche, and return jets. You can use a pool leak test kit or the red pH liquid to look for the leak. With the pool pump off, squeeze a few of the red drops near the suspected leaks. The leak will draw the dye in if there is a leak present. You could then fix the leak with underwater epoxy. We recommend calling a leak detection company if you can’t locate the leak.
Thanks, Rob, for your response. I just recently purchased this item (Marlig Fix Pool and Spa Leak Sealer 32 oz). It’s scheduled to be delivered tomorrow (Thurs, 5/2). Do you have any experience with this product? Also, what is the proper size for a Weir (Skimmer Flapper). My skimmer size is approx. 8-1/2 (W) x 4-1/2 (H). I’m not sure that my current Weir is the proper size. Thank you!!
Debbie
Me again… Yesterday and today, when the pump turned on to begin circulation, I had lot’s of air bubbles from my return jets and in-floor cleaning heads. Could this be the cause… Air in the pipes/equipment? And, not a leak?? Thanks AGAIN!!
Debbie
Air bubbles are a sign of a suction side air leak. You wouldn’t be losing 1-2 inches of water while the pump is running from an air leak. It sounds like you may have a couple of problems. Check out the section in the article above titled “Air is the Enemy”. This will give you an idea of where the bubbles may be coming from.
I do have experience with the Fix-A-Leak. It’s a great product for sealing leaks in the plumbing. Make sure you follow the directions on the bottle. As far as the skimmer weir, we’d have to know the make and model of the skimmer. Is there a part number on the underside of the skimmer lid or on the rim of the basket?
Rob, what hours of the day can I call you? Preferably, this evening (Thursday night) or tomorrow (Friday) in the AM. Contact # would be helpful as well! Thanks! — Debbie
Hello Debbie – I’m not on the phones but you can call our technical support line at 407-834-2200. Our techs are available 9am-6pm EST Monday through Friday.
Hi Rob,
I contacted Tech Supports via phone. Thanks for directing me there. However, I forgot to ask about the Skimmer Weir. My skimmer lid has this information: Haywood Skimmer – SP1070 (Max-55 G.P.M. / Min-10 G.P.M.)
Hello Debbie – The replacement weir door for the Hayward SP1070 skimmer is part number SPX1070KHR.
Oops, Skimmer Manufacturer is “Hayward” not Haywood, but, I’m sure you figured that out! SMILES.
Just replace the pump, now only one jet is working.
Did you purge the system of air after replacing the pump?
Need help…
We have a fiberglass pool and spa with no equalizer line connected between them. We thought we had a leak because we were losing water so fast when pump is running. So the spa has been off for two months. Got tired of chasing the leak because nobody can find it so we filled the spa back up and now have weak jets. When the air blower is turned on only 3 of six get bubbles.
I’ve changed the jet inserts
Filter psi is around 17
Installed a new pressure gauge
Checked for clogs on the motor impeller
No air at the pump
Cleaned the filters
Installed a new check valve on blower
Any more ideas????
If you do see any obvious wet spots above ground then the leak may be underground. The usual spot is the main drain, it’s sump or return line. Generally, you won’t be able to tell unless you dig down to inspect those suspect spots.
I have a in ground pool running high psi. And the sand has been replaced and backwashed regularly. However the water still looks cloudy I have no algae and the chemicals are perfect. I have noticed the jets are not as strong and one will stop working all togetjer
.
Hello Tanya – You’ll probably need to backwash the sand filter several times a day until the pool clears up and the PSI stabilizes. Backwash the filter each time it rises 10 PSI above the clean starting pressure. I would also recommend trying a product by Natural Chemistry called Pool First Aid. It will clear up the pool and free the filter of any oils and non-living organic build-up.
Oh sorry. I meant to put my name in. Above. It’s Mike from Northern California.
I haven’t got a straight answer from our pool contractor yet except he said we need to find som”extenders.” Not sure what that means. We have a spa seperate of the pool and it heats but no air bubbles. No jets work. It’s all brand new. The spa is 60 ft from the pool house pumps, heaters and filters There is an air intake pipe coming out from under the spa about six feet away from the spa underground and sticking up above the spa height. The contractor said normally the air intake is right next to the tub but it makes a lot of noise and wanted ours to be quiet and away. Now there is no air.
I keep asking for it to be fixed and it seems they are dragging their feet for some reason unbeknownst to me.
Hoping you could share some of your expertise as to why this all may be happening. I’m a layman and just trying to understand what the issues are.
Thank you for your time and consideration.
I saw bubbles this morning and now jets aren’t working. Ideas??
Hello LaRonda – We have several ideas for why your jets are not working. Part 1 of this article should have a solution to your problem.
Hi! A leak detection company came out Mon and found a leak in one of my jets. Yesterday they cut up the concrete and replaced the jet. After they left, it took 4 hours to fill the pool enough to run the filter. The 2 jets on the steps worked with excessive pressure but the new jet and the other one in the deep end are not working at all. I have called the leak company 3 times, I left a voice message last night and 2 today explaining the problem but they do not return my call. My psi is 18. It usually runs 10. My pool is clear. What could be wrong with those 2 jets. I will say I had no problem with the leak company who fixed the leak until after the work was done and the checks written.
Hello Mae – If you and someone else can cover up each of the working jets with your hands, see if the non-working jets begin to flow. If they do not work, my guess is that the leak detection company capped those lines. They need to come out and correct that problem or I would stop the payment on the check.
We tried that and it didn’t work. See my update above. We found out someone had mislabeled the shut-off for those 2 jets as well as a couple of other things with a sharpie. I think we are straightened out now! We just bought this house last year so the inground saltwater pool is new to us and we are still learning. Thank you for the reply! I really was considering a stop payment on the check.
We’re glad that your issue was resolved and that it was a simple fix. We hope you enjoy the rest of the summer!
Update – I called again this a.m. and was able to reach the tech. They had accidentally left the 2 jets turned off. Once those jets were turned on, the psi dropped to 14 which is fine, although a little high. We have replaced the salt and all the chemicals to balance the pool. (We took a sample in and had it analyzed) In 48 hours we can do a quick backwash and rinse and the psi should return to normal.
Hello. I am at a complete loss. I just replaced my Hayward sand filter with a new one. Same exact filter just needed a new one. When I turn the pump on the return jet has a nice strong output for about 10-20 minutes, then it slows to virtually nothing. I backwash the filter and then start it up again and it works fine for another 10-20 minutes and it is a never ending cycle. all of the baskets are clean. I don’t know what I could be missing.
I should also add the the pressure gage is staying the same when I first turn it on to when it slows to virtually no return from the jet. It is not spiking or dropping.
Although new, the pressure gauge may be defective. You should see some PSI fluctuation from when the filter is clean to when it starts to fill up and the water flow slows down. Make sure the water level is at least halfway up your skimmer door opening. Is the pool crystal clear or is it green/cloudy? Is there any air inside the pump strainer?
The water is a cloudy blue. It was very green when we started this process so I thought that maybe that was why I was having to backwash constantly, but now as it starts to clear up I’m confused as to why it is still doing it. I have watched the pump strainer and I see no little air bubbles. I’m going to try the smoke trick to see if air is getting in anywhere because that is the only thing I can think would be the problem.
I’m treating yellow algae with yellow & black magic & shock overnight. The PSI gets high & the flow on my return jet stops about 30-40 mins after backwash. Would it be ok to run filter on recirculate overnight to ensure the chemicals are properly distributed in the water? I have a sand filter.
Hello Sue – Yes, you can run the filter on recirculate in order to properly distribute the chemicals.
My pools been cloudy since opening. Pool guy said I need to get new grids for my DE filter. New grids installed, but it takes a while for it to prime, maybe double or triple the time from old grids. Also, jets work for the first half hour and then die off. I turn off filter, turn back on. Jets start up, but then die out between 10-40 minutes after restarting filter. Any advice?
Hello Maryanne – What is the PSI reading on the filter gauge when the jets start to slow down?
I have this same problem, my PSI reading is 26, thanks!
Hello Bonnie – A PSI reading of 26 is pretty high. What type of filter do you have? Have you cleaned it? Does the pressure drop after cleaning the filter?
I’m having the same problem I’m using a Hayward sand filter and a Hayward power Flo LX pump after backwash jets are strong but died down within an hour. We changed the sand last week and still having the same issue. We have flexible hose coming from the pool to the pump that are not clogged. The only thing I can think of is the Impaler maybe clogged a little? Going to check that today. Do you have any other suggestions?
Hello Rachel – Yes, it could be a clogged impeller. If the water is cloudy or green, the filter could be filling up quickly. This would cause the jets to weaken within an hour.
I have only one return jet with low pressure. I’m assuming that means there is something blocking it.
Hello Sharon – Look at the PSI reading on your filter’s pressure gauge. If the PSI is lower than normal, read Part 1 of the article above. If the PSI is higher than normal, read Part II.
hi sharon, been a while since your post, but what solved the problem? I have a similar issue, but it’s when i switch to spa mode (pool/spa combo) which bypasses the pool returns (which has normal pressure) and splits the flow between two bullfrog jetpacks. One jetpack has normal pressure and the other jetpack has low pressure. all valving appear to switch to normal operating position for spa mode.
I have very little water coming from the suction side coming into the filter on all cycles: filter, recirculate, backwash and even waste! Do you think it’s a clog or damage to underground piping?
Thank you for contacting Inyo. Part one of the article covers the common reasons why you would have low flow through the system. If you have ruled out all of those possibilities, then you may want to contact a leak detection company to come out and check the plumbing.
The inlet velocities through the orifice are too low in our in ground swimming pool.
How do I increase the velocity? Smaller orifice ? Currently 3/4″ . Wha t is the calculation I can use for this flow in FPS?
Hello Deacon – You could increase velocity by increasing the HP of the pump motor. Using a smaller orifice on the return jets could also increase velocity. Check out the following page for info on FPS calculations. http://www.anotherperfectpoolnews.com/2011/12/12/flow-rate-and-water-velocity/
Great …Thank you for the information…
Hi there,
We replaced our pool motor, shaft seal,
Cleaned the impeller and strainer basket but there is mo suction on the pump. Backwash works but when the pump is set to filter no water is getting taken in. It was working with our old motor about a week ago but then we replaced the motor because it kept tripping the circuit breaker.
Any thoughts? Thank you!
Thank you for contacting Inyo. Does the pump work if the filter valve is set to recirculate? Do you have a sand or DE filter?
I have same problem as stumped..new filter, etc. Main drain and skimmer do not work together if both open but work seperately. They do work on recirculate. I have a sand filt
Great article and information. My pool works on waste, backwash and rinse, but it has very low presssure on filter and recirculate. Any ideas?
Sounds like there is an issue with the plumbing after the filter. Regular and filter are the only settings are the only ones that send water back through the return to the pool. Have you checked blockages or closed valves?
Great information provided
Thank you
You’re welcome and thank you for the feedback!
When the filter is on recirculate…pressure from jets is strong…when I turn it to filter…pressure from jets is weak and psi is very high. Backwashing temporarily fixes it but only for a few minutes. I have a Hayward de4800 filter that’s about 15-17 years old…there are bubbles in the pump window…Thoughts?
I’m having the SAME problem!
time to change the sand. sounds like your sand may be too fine also
Any suggestions on removing a direction with broken tabs on a deck jet? Wanted to swap eyeballs for a different water effect and when I went to unscrew it the tanks broke off.
I have two jets only one it working what can i do