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 -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 -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 ,000. That section of the deck needs to be removed, the skimmer replaced and re-plumbed 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 article.