What Does The Swimming Pool Pressure Gauge Do? Everything You Need To Know


The Simplest Part On Your Swimming Pool

There isn’t many parts on your swimming pool that is as simple as the pressure gauge inside your sand filter.  The pressure gauge really only has one basic job and that is to help you know when your sand filter is getting close to full from dirt and debris that it has collected in the previous days from your swimming pool water.

It truly is one of the simplest parts your swimming pool does have.

How It Works

A swimming pool pressure gauge.

The pressure gauge shows the current amount of pressure that is being pulled through the swimming pool pump and filter.  Some gauges have a start and clean mark as this one does.  After you backwash your reading should point toward the start setting.  If it does not you can adjust the dial accordingly.  Once pressure has built up to the clean filter setting you will know it is time to backwash.

The pressure is measured in PSI or pounds per square inch and the needle on the gauge will point to the exact amount of pressure currently being pushed through all the pools hoses that returns the clean water back into your pools water.What should your pressure reading be?  I can not answer this specifically because each and every pool pump and filter will be different based on various factors.  Some of the factors that causes differences in the normal pool reading are the amount of horse power your pump has, the size of your filter and hoses and even the age of the sand currently being used in your filter.

The only way to tell what the normal or clean reading should read is to record the gauges reading as soon as you have placed brand new sand in your pool filter.  This is true because there has not yet been any filtration with the sand thus making a true clean reading.

Alternatively to get the clean pressure reading backwash your swimming pool until the water is completely clean and rinse as usual prior to returning your sand filter back to the filter mode.

Once you have returned your swimming pools sand filter back to the filter setting, read the current pressure shown on the pressure gauge.  Since you have flushed all of the dirt out of the filter and the sand is now back to the clean state, you will now be getting the reading that the pressure gauge shows once the filter is clean.  This is your normal operational pressure for the swimming pool you are using.  Also as your sand gets older, the clean pressure setting may increase slightly as the sand begins to lose some of its ability especially after the sand is a few years old.

When To Backwash?

It is a good ideal to backwash your pool about once per week.  Of course for light usage swimming pools, it may only be necessary once every other week or even every few weeks.

The pressure gauge takes the guess work out of trying to determine if your pool needs to be flushed out by performing a backwash.

When your pressure gauges rises 7-10 PSI  above what the reading was when it was clean (last backwash), it is close to time to backwash your swimming pool once again.

For example:  You flushed your swimming pool and the pressure reading once completed and clean was 12 PSI.  You have now used your pool and even vacuumed it once and now it reads 20-22 PSI.  This is an indication your swimming pool probably needs to have a backwash completed.

Dirty water coming out of the blue backwash hose.

Backwash until the water becomes clear.  You can also use the sight glass found on your sand filter to determine when the water is clear.

pressure gauge is not working

While these gauges are extremely simple and require little work during the regular season they do at times fail.  If the pressure gauge is not reacting to your swimming pool pump while it is running, you should replace your pressure gauge.

There are a few reasons why your gauge may have quit working including the most common issue is off season deterioration.  This occurs after you have closed your swimming pool for the season.

If your gauge is left in the elements for the winter months it reduces the chance of it working the next pool season.  To avoid this when you close your pool and drain or plug your water from all the hoses that lead to your pump, remove the pressure gauge and place it in a safe place inside your house.  This will allow the gauge to stay in warm conditions and remain in the same condition during the opening of the following season.

Replacing the pressure gauge with a new one however is not all that expensive and is relatively easy compared to other part replacements you will encounter as a swimming pool owner.

To replace your pressure gauge you simply need to have the following items.

  • Obtain another pressure gauge (preferably new) that is in good condition and works.
  • Have some plumbers white tape available in case of leaks after the new gauge has been installed.
  • An adjustable wrench may also be necessary when removing the old gauge and adding the new one.

Once you have the above items you can easily turn the old pressure gauge counter clockwise that is attached to your sand filter to remove it.  Once removed add some plumbers tape to the new ones threads and place it on your sand filter.  It doesn’t get any simpler!

I do recommend you do a backwash to allow your sand to be completely clean to establish the normal reading on the gauge during the first install.

Once you have your filter cleaned you should record the current reading shown on your pressure gauge and anytime the pressure read more than 10 PSI above that reading, perform your backwash.

It is also a good idea to have your backwash hose routed away from an area you preferably do not want to get flooded and avoid sending the water toward your neighbors yard.  You will need to check local laws and ordinances in as well before you send the water into city streets or drains.

Check Weekly

The most important thing you can do for your swimming pool is having a routine schedule.  Set at least one day per week to check your pool pressure gauge while performing your routine cleaning, testing the water and while adding chemicals.

After a few weeks you will be able to predict ahead of time if your pool pressure gauge is likely going have a high reading.  Some pool owners may find that the pressure doesn’t climb all that quickly while others may barely make it a week before flushing is necessary.

Why might my pool pressure gauge increase quickly requiring me to backwash my swimming pool more frequently?

  • The most common reason for this would be heavy usage.  If you have numerous guests in your pool daily, your swimming pool gauge pressure is likely to increase quicker.  This is because oils, dirt and hair will wash off the bodies of the swimmers.  If your pool is in a grassy or area where there is dirt, each entry into the pool will bring more into the pool water that requires filtration by your sand filter.
  • Mother nature can also be a factor.  If you live in an area that has a lot of wind or frequent storms that bring dust, leaves and other debris into your pool water, then your going to see that your pool gauge will increase more rapidly.
  • Frequent vacuuming or if you have an auto cleaner always picking up from the bottom of your pool.  This is a good thing for sure!  If you are able to vacuum daily and keep the bottom of your pool clean, Kudos to you!  However a lot of people only have time to do this about once per week or sometimes even less.  While there pool water is still going to remain clear as long as they keep there chlorine levels in check, the bottom may have things down there.  If your one that has those sent to your filter on a daily basis, your pool pressure gauge will rise quicker.
  • Algae is one of the worst nightmares of many pool owners and no matter what they say, everyone at some point has had algae in their pool.  If you recently had an algae outbreak and you added algaecide or increased your chlorine levels (aka. shocked the pool), your filter has likely picked a lot of the dead algae up.  On the other token, if you haven’t killed the algae your sand filter likely is full of green algae.  Either way this will definitely cause your pool pressure gauge to spike and rather quickly until you get it back under normal swimming conditions.

Final thoughts

The swimming pool pressure gauge is not the most exciting part to your pool, but plays a very important role in helping pool owners by giving them an indication on when their sand filter needs to be cleaned.

It also may be a good idea to inform your other family members that use the swimming pool frequently about the pool pressure gauge.  Even if they do not perform the maintenance, they could notify the proper person when a backwash may be needed.  This is extremely helpful when the person maintaining the pool, is not a primary user of the swimming pool.

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