All You Need to Know About Your Pool Filter Pressure Gauge

Don’t confuse price tag with value. Although a pool filter gauge is relatively inexpensive—you can probably get one for under twenty bucks—it’s actually a pretty good personal pool technician, just one that can only communicate in numbers and can’t physically do any of the manual labor. Sorry, you’ll still have to be the one to scrub your pool down.

If something’s gone wrong, your pool filter gauge can be your first heads up. And all you have to do is make sure you’re looking—and that you know what to look for. I’ll explain what a pool filter pressure gauge is, how to determine your normal operating level, what to do if your gauge reads too high or too low, and how to know when it’s time for a replacement. Pretty soon, you’ll have yet another tool for seamless pool care—all thanks to this tiny little dial.

What Is a Pool Filter Pressure Gauge? 

A pool filter pressure gauge displays the exact pounds per square inch (PSI) of your pool filter, which requires some pressure inside its tank to function. When the filter pressure is normal, water is flowing through it fairly seamlessly, and your equipment is operating smoothly and safely. If that pressure is increased or decreased too far, which happens when something changes the water flow, it can wreak havoc on your greater circulation system—and lead to some pretty costly replacements or repairs.

The pool filter pressure gauge is a small dial attached to the top of your filter, and looks a lot like the old-fashioned thermometer you might’ve used for last Thanksgiving’s turkey. We can thank our lucky stars that it was invented and usually comes along with a pool filter: it’s the only way to monitor the filter’s pressure. It’s just one of the many inventions I can’t do without—like chlorine, sunscreen, and sports team-themed floaties.

How Do I Determine My Normal Operating Pressure?

This one is tough, because your pool filter gauge is simply not one-size-fits-all. Your normal operating pressure depends on a few factors: the size of your pump, the horsepower of your pump, the filter’s size, and the current cleanliness of your filter.

Just because your filter’s normal pressure is unique doesn’t mean you have no way of determining it. All you have to do is keep an eye out when you first install your filter media, whether that’s sand, D.E., or a cartridge filter. Once you turn on your pool pump, that number on your gauge is your new baseline pressure. And after you clean it out for the first time—meaning you backwash your sand or D.E. filter, or rinse down your cartridge filter with cleaner—write down that PSI number, too. These two numbers will give you a normal operating range.

Didn’t check with your media was replaced? In the meantime, stick to the number that your gauge displays after you clean your filter. Don’t worry—eventually, all media does need to be replaced. If only everything we did to our pools was permanent. Big sigh.

Is your cartridge filter on its last legs? Save money on a replacement filter that you can trust, like the Replacement Filter for Hayward Pool Products. It’s the most economical replacement filter on the market, and is built to last. 

What Should I Do If My PSI is Too High?

Okay, so your PSI is above your normal operating pressure. No biggie! At least, not at first. It’s actually good to have a slight higher pressure in your filter—it means that all the contaminated gunk that your filter has caught from your pool so far is actually helping to catch more. Sort like a snowball effect—that isn’t fun to throw at your friends.

How High is Too High?

This one’s easy. Once your pressure hits 10 PSI higher than your normal operating level—that is, the highest number of your range—it’s time to make a move. This is a staple of your normal maintenance routine: if your PSI reaches this point, it’s time to clean your filter. For a cartridge filter, this just means hosing it down or even dousing it with a special cartridge filter cleaner. For a sand or D.E. filter, you’ll need to backwash your filter. Just make sure that you’re backwashing it to the right place—you don’t want to save money by taking a DIY maintenance approach just to get slapped with environmental fines from your local government. Yikes.

Did cleaning or backwashing your filter do zilch for lowering your PSI? It’s probably time to switch out your filter media entirely. This is actually great, if you never knew your normal operating pressure—don’t forget to write down your gauge number after your filter media is spanking new.

PSI Still Too High?

Thankfully, the filter pressure gauge doesn’t need to operate alone. It also has an air relief valve, which keeps pressure levels in check. If your PSI is still too high, there’s a chance that your filter is full of not just water, but air. If you’ve been hanging around here for a bit, you know that air in your pool’s circulation system is bad news.

So how did air get into your filter? Well, the first thing to check is your water level. When you look into your pool, you should see it’s filled to about halfway up your skimmer door. If it’s low, your skimmer is probably sucking air into your pipes, which goes through your pool filter and pump—and has the potential to wreak havoc along the way. The last thing you want is for your equipment to get too hot because its moving not water, but air.

This is when the air relief valve is a lifesaver—of you know, money-saver. While running your pool filter, open the air relief valve, which sits on top and looks like a small handle-like protrusion. Continue running your filter until water begins to leak from the valve, or the hiss of air stops. Repeat as necessary to decrease your pressure. It might also be a good time to prime your pump. If there’s air in the filter, there might be air elsewhere in your system—though I hate to say it.

Is your pump not up to the task? Try the powerful 1.5 HP Variable Speed Blue Torrent Thunder In-Ground Swimming Pool Pump—it pays itself off in under a year, is eligible for rebates, and also comes with a lifetime warranty. As customer Eric D says, “Day one, I fired this pump up and it ran clean and fast.” 

All you need to know about your pool filter pressure gauge

What Should I Do If My PSI is Too Low?

Though it might seem like a high PSI is really what to be worried about, a low PSI on your filter pressure gauge can also indicate some pretty serious hurdles in front of you. What a low PSI indicates is that water is just not flowing as it should be. The cause? Well, we’ve got options.

How Low is Too Low?

If your pool filter pressure gauge reads at least 5 PSI lower than your normal operating pressure, it’s time to get troubleshooting. Most often, it means that you have some unclogging to do. Better get some gloves on.

Most likely, the blockage is located somewhere before the filter. That includes your skimmers and drain covers. Plus, you’ll want to check your pump basket and pump impeller to make sure everything is in order. Don’t be surprised if you find an unsightly tangle of leaves, dirt, twigs, and other junk just waiting to be removed. Ick, I know—but someone’s got to do it.

Unclogging Didn’t Work. Now What?

If you didn’t find any clogs, or you did and your pool filter gauge is still showing a too-low PSI, there’s a good chance you have a leak on your hands, and yet another chance that it’s probably your pump. Check your pump carefully for any leakage. If you find one, you’ll want to repair the leak or—and I know I don’t usually say this—hire a professional. My recommendation is to view this as a great opportunity to make a long-term, cost-saving decision by getting a variable-speed pump. If you get the right one, it’ll pay itself off in under a year in energy saved. How’s that for a silver lining?

If a variable-speed pump is sounding pretty good right now, try the Blue Torrent 2 HP Variable-Speed Pump. It’s ultra-powerful, comes with a lifetime warranty, eligible for rebates, and pays itself off in under a year by energy saved. As customer Bill Britton says, “Runs great. Super quiet.”

How Do I Know My Pool Filter Gauge is Kaput?

If you’re still scratching your head about why your levels are too high or low, it might just be your pool filter gauge itself. With the pool pump off, check your gauge—it should read zero. If it doesn’t, or if it reads zero when the pump is on, your gauge is probably ready to go. Examine the gauge dial for warping, which could indicate that you’ve got a broken gauge. You can also give it a flick, and see if the pressure momentarily pops up. If its unresponsive, its time has come. Again, replacement gauges are usually less than twenty bucks.

All you Need to know about your pool filter pressure gauge

The Pressure’s Off!

When it comes to your pool, prevention is key. The earlier you know there’s a problem, the easier you can solve it—before you ever have a cloudy pool on your hands. And now that you’re in the know, you’ve secured yet another line of support for keeping your pool running properly with minimal effort. Your pool filter’s pressure gauge will let you know when you need to buckle down—for now, remember why you have a pool in the first place. I’ll tell you one thing: it’s not because you wanted another responsibility. So dive in, and enjoy.


Related articles:

Sand in Your Pool? Here’s Why—And How to Fix It

Chlorinate Your Pool in Three Easy Steps

The Safest Way to Store Your Above Ground Pool For Winter


*Hayward® and Hayward® Pool Products are registered trademarks of Hayward Industries, Inc. Asia Connection LLC has no affiliation with Hayward Industries, Inc.

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