Most of the time you can tell pretty quickly when/if you’ve got air entering your system.
There’s a couple of real giveaways…
1. The filter pressure is lower than normal – in extreme cases, if there’s no water flowing through the system, there may be no pressure at all.
2. Bubbles coming out the return line. When firing up the equipment it’s typical to see this for 30-60 seconds. If it continues releasing bubbles…there’s air entering the system.
Think of your pump as a vacuum – it’s job is to get the water from the pool to the equipment…hence the name “pump”. It’s constantly pumping water.
Anytime air enters the system, this can reek major havoc on the equipment…specifically, the motor.
Pumps are designed to pump water…not air.
If a pump runs dry for an extended period of time, it’ll burn up – costing a couple hundred bucks to replace. Not a very good scenario. 
If your filter pressure is running lower than normal, or if there’s no pressure at all – here’s what to look for:
1. Check the water level to the pool. If there’s no water getting in the skimmer, there’s no water getting to the equipment. Pretty obvious, but I see it all the time.
2. Check the pump lid for any cracks. Even a small fracture can cause air to enter the system. If there is a crack, don’t try to fix it…replace it. They’re relatively inexpensive.
3. Check the pump lid o-ring. Remove the pump lid -there’s an o-ring that “sits” beneath the lid and the pump to seal it ensuring there’s no air entering the system. A tear, crack or pinch can cause air to enter the system. Again, don’t try to “rig” it to fix the issue. They run $5-12 – replace it. These should be replaced every 2 years or so.
Hey, your car needs basic maintenance right…the occasional tune up, oil changes, tire rotations, etc. Chances are, your pool investment is pretty close to what you paid for your car. Don’t run it into the ground.
Treat it to a basic maintenance “regiment” and you’ll save yourself loads of cash down the road and likely prevent most, if not all, major repairs.
4. Check for any “wiggle” room at the pump nipple. This is the section of the plumbing that goes into the pump. If there’s any “play”, even a smiggin’, this can cause air to enter the system. No bueno.
If you have basic plumbing skills, this is a task most can do themselves. If not, you can hire a technician to knock it out for you – typically around $50-90 (this will vary a bit depending on how the plumbing is setup at the equipment).
5. Check for any cracks in the skimmer. This can also cause air to enter the system. Fairly rare event, but it does happen – and it’s not a pretty situation. Think of your pool and all the weight it carries…over time, it settles like a home does. As a home settles, it can cause counter tops to separate, floors to crack, etc.
Your pool is no different. Over the years, it will settle and shift. This is exactly why most pools built after the mid 90′s are built with a different mixture of compounds – allowing for “play” room as the pool shifts and settles in.
Replacing a skimmer is not only a fair amount of work, but it can also set you back over $1,000. That section of the deck needs to be removed, the skimmer replaced and replumbed at that section.
Again, this is a pretty rare event, but it does happen – if you have an older pool, you’re more likely to experience it.
And there you have it…the top 5 causes of air entering the system.
There are others as well, but they’re so rare, I won’t address ‘em in this post.
I hope you enjoyed this and learned something new…or maybe reinforced something you were already aware of.
All the best,
Terry Duff
{ 22 comments… read them below or add one }
Terry, your timing on this topic couldn’t have been any better. I live in NV and noticed last weekend my filter pressure was 7 PSI – it’s usually at 15-17. Glad my motor didn’t go out!
Thank you for the continual updates – oh, and I purchased The Chemistry Wizard…just my 2 cents, but you should TRIPLE the price for it!
Candice
Glad the info helped Candice. Thanks for the feedback on TCW – glad you benefited!
Terry
Thanks, my pump won’t hold water when off and takes a very long time to reprime when started. After your article I found the union was a little loose. I tightened and think I have solved problem.
@ Lee – that’s music to my ears. Love hearing about problems being solved!
All the best,
Terry
One more or what could have been added to low water to the skimmer is,… The skimmer weir getting stuck in the closed position. Water will seep in but not allow enough water to keep the pump from losing prime.
Terry, have trouble with our indoor heated pool loosing cholorine and ph level too high all the time. temp is usually about 88degrees and we keep it covered with a bubble cover to help keep in the heat. we use liquid muraic acid and cholorine tablets. i have looked but havent’ seen where you have addressed this in an indoor pool situation. thanks. george.
Terry, I am a fairly new pool owner, 2 years. Last year we continually shocked our pool. kept taking in water,, couldn’t keep chlorine. I know this was a hot summer, but i don’t want to tell you how much chlorine we put in our pool, among other “fixes”. When i poured the chlorine in, the pool actually became more “murky white” with the addition. Finally, we closed early. At the end of the summer, i talked on the phone with a knowledgable person (instead of my local pool dealer who kept saying they didn’t know, the summer was hot, telling me to shock every night or every other, which didn’t help either). He said that i need to change the sand before i open this year? He says the sand either has something in it or has channeled? Should i change my sand every year? does this sound like a fix? we have tried everything and i don’t want another summer like last… Our neighbor did not do anything like us!
Hi, timely post, thanks. My issue is that when there is no pool vac and pipe attached to the skimmer, there is no problem with air getting into the pump. As soon as the pool vac and pipe are attached via the skimmer – the salt cell glass starts to fill with tiny bubbles, until there is enough of a build up for the pressure to drop. I have replaced the pool vac pipe as an obvious source of sucking in air at one of the joins, but the problem remains. Appreciate any advice you might have. Thanks
Terry; I have this problem of loosing the prime to the pump when I open the valve to the main drain of the pool. If I use only the skimmer port the pump works fine and as soon as I open the valve (more than 30% ) to the main drain I loose the flow. I believe there’s a small crack in main drain line do you have any suggestion on how we can fix it without digging up the whole yard? Is there a way to pin point this crack in the pipe?
Terry when l prime the system and run l shut it off all the water in the large filers tank drain down, until there is no more water in the system and to restart l have to repeat the same operation, what does it mean.is it my pump seal or what.
Air is entering the system causing “backflow” to take place. It could be one of many locations. I’d check the pump lid o-ring & filter o-ring as these are the 2 most likely locations. Use some Magic Lube on ‘em as well to help seal it.
Terry
@ Bob,
Depending on the valve on the suction side that regulates where the suction is coming from there may be air entering at the o-ring. This is common with standard Jandy 3-way valves and the replacement o-ring runs about $4.00.
There could also be some “play” in the main drain valve allowing air to enter at that location causing the loss of prime.
Possible, but highly unlikely there’s a crack in the main drain line that’s causing this. Start with the most likely scenario first.
Terry
@ Jeremy,
More than likely air is entering directly from the vac (or vac hose) itself when it’s connected to the skimmer. Make sure you submerge it (prior to attaching to the skimmer), and manually suck the air out of the line – then connect it to the skimmer. Should knock it out.
Let me know if that doesn’t do the trick sir.
Terry
@ George,
Likely a CYA issue – test and adjust accordingly.
If that tests out OK, test for phosphates.
Terry
Terry,
I appreciate your willingness to help with our swimming pool problems. I have a question about the Nature-2 Mineral Sanitizers. My salt water pool will be starting its 7th season this summer. I keep it open year round. When my pool was installed they installed a Mineral Sanitizer. They recommend the cartridge be replaced every 6 months. The cost of the cartridge is around $100.00 each so that is $200.00 per year. $200.00 times 6 is $1200.00 so far. My question: Is this a necessary expense or is this just a money maker for the pool companies? If this is necessary would you please explain how it helps?
Also, my pool has a liner. The first liner lasted only 5 years before it started coming apart because of UV damage. Is there some product that I can apply to the liner to extend its life? As I am sure you are aware the price to have a new liner installed is around $3000.00.
Again, Thanks for being here and helping us out.
David
Thanks for the info, i own a second hand old dough boy pool and it seems that everything is going at the same time. I just replaced the pump because we thought it had a hair line crack but only after repacing the orings and shaft on the old one first. after repairing it i was still getting air. And guess what, it was the skimmer, seems my husband neglected to cover it last winter and there is a hair line crack where the bottom hose attaches. Can this be fixed with an appoxy / glue or do i have to buy a new skimmer this summer? The local pool company was great about the pump they credited me the cost of the repairs of the old pump to cost of the new one. Now i can see that is was probably not the pump at all but the skimmer. Live and Learn!
There doesn’t seem to be any air bubbles coming out of the lines, but the pump makes a low grinding sound. Is this likely air getting into the line?
@ Bonnie,
Check 2 things…
1. Look for a clogged impeller. Not the likely issue, but a possibility if it’s clogged by a rock or other debris impending it from spinning properly.
2. The most likely scenario is the bearings are going/have gone out. This typically causes a loud screeching/grinding noise – it will progress over time. If this is the case, you’re better served getting the motor rebuilt or replacing the motor with a new one.
Terry
Very well done. I appreciate a site that is dedicated to true swimming pool knowledge and not just promoting a product or service. The internet is the future of our industry!
I have a problem, and I hope you have an answer….
We just bought an intex salt water system for our above ground pool, we added all the salt we were supposed to, and made sure it dissolved, we have been running the pump and the saltwater system for 48 hours now and are still getting 0′s on the chlorine and copper levels. the ph is a bit high 8.5-9, that wouldn’t effect it that much would it? Not sure what else to try. please help
Thank you
Dustin
Hi Dustin,
Confirm the cell is functioning correctly and there are no warning lights coming on. Also, make sure cyanuric acid levels are appropriate – this is still needed with a salt system to protect the chlorine. Without it, any free chlorine can dissipate rather quickly.
The pH issue here isn’t relevant although it should be addressed once you’re showing chlorine.
Terry
Terry..I have an in ground pool with Nautilus DE filter. Recently I removed the filter, cleaned it thoroughly, inspected the grids for any tears, and re-installed. I added 7 lbs of DE per the manufacture’s directions making a slurry and slowly pouring it into the skimmer. The pressure is fine and everything seems to be working EXCEPT the following day there was a good amount of DE in the pool near the main drain. I think there is air in the system since periodically I see air bubbles coming out of the returns. There doesn’t seem to be any water leaking around the pump or filter. The bleeder screw on the top of the filter doesn’t let out much of anything. Could I have one or more bad o rings on the filter housing or slider valve ? Could the latter cause DE to get into the pool ?