Pool Filter Pressure Gauge Reading 0? Important Reasons with Solutions!

Why is Pool Filter Pressure Gauge Reading 0?

That seems strange! Why is your pool filter pressure gauge reading 0? A pressure gauge reading of zero means that there is no pressure being applied to the filter. Something is clearly wrong. But don’t worry and certainly don’t panic!

A pool filter pressure gauge reading 0 is a possibility. Of course there will be a reason for it and there will be a fix as well. Believe it or not sometimes the reason can be pretty silly such as a stuck needle. Just a tap on the gauge glass will fix the issue!

However, more often than not the reason will be a bit more complex. But not so complex that it can not be fixed. The problem, if any, is figuring out the reason for the pool filter pressure gauge reading zero.

In this post, I look at the most common reasons for the pool filter pressure gauge reading zero and tell you the best fix in each case.

What Should the Pressure Gauge Read on a Pool Filter Be?

Certainly not zero. When the filter is completely clean, the pool filter pressure gauge reading is typically between 10 and 25 psi.

A filter can be considered to be completely clean after a successful backwash or better still just after the filter media has been changed.

The actual reading, of course, depends on several factors such as filter and pump specifications. Whatever it is, you must make a note of it as the “normal” pressure reading for your pool filtration system. 

This number is important. When the pressure reading is around 10 psi more than “normal”, you need to backwash (in case of sand or DE filter) or clean the cartridge filter.

The pressure reading should return to “normal” after a successful backwash or filter clean, as the case may be. 

Assuming that the pressure gauge is not malfunctioning and the needle is not stuck, the pool filter pressure gauge reading 0 or very low means no or very little water is flowing through the filter. 

These are the possible reasons:

1. Clogged Skimmer or Pump Strainer Basket

A clogged skimmer or pump strainer basket is, in fact, one of the most common causes for pool filter gauge reading 0. Maybe you were on a vacation, extremely busy at work or just a bit lazy. 

A storm can blow up dry leaves or other yard debris into the pool and ultimately into the skimmer or pump strainer causing it to clog. The water flow to the filter gets restricted or totally cut off, causing the pressure inside the filter to drop.

The solution to this problem is relatively simple. First, turn off the pool pump to prevent any damage to the system. Remove the skimmer basket and pump strainer basket and clean them thoroughly. Use the garden hose to wash it clean after extracting the muck with your fingers.

Once the basket is clean, replace it and turn the pump back on. Check the filter gauge reading again to ensure that the pressure has returned to its normal range.

2. Clogged Pump Impeller

The pool pump impeller is what sucks in the pool water and then pushes it through the filter at a pressure. At times the debris can deposit on the impeller and even clog it. 

When the impeller is clogged, the pool pump has to work harder to move water through the system. Obviously the amount of water flowing through the pump drops and you may see the pool filter pressure gauge reading 0 or very low.

Moreover, a  clogged pool pump impeller can cause the pump motor to overheat and even burn out, leading to more serious and costly issues.

It is possible to clean the pump impeller, but you must be very very careful. Turn off the pool pump and disconnect the power source. 

Remove the pump strainer lid and strainer basket. Locate the impeller using a flathead screwdriver or similar tool. You can remove any stuck debris, such as grass or dry leaves, from the impeller blades with the screwdriver.

Once the impeller is clean, reassemble the pump and turn it back on. Check the filter gauge reading to ensure that the pressure has returned to its normal range. If the pressure does not return to normal, there may be additional issues.

3. Multiport Valve (MPV) Setting

When you see the pool filter pressure gauge reading 0 or very low, make sure to check the multiport valve (MPV) setting. The multiport valve (MPV) has 7 settings of which 3 settings allow the water to bypass the filter media.

If the multiport valve (MPV) is set on “Waste”, “Backwash” or “Recirculate”, water will bypass the filter media and the filter gauge will not show any pressure reading. 

If the pressure gauge reading is normal when the multiport valve (MPV) is set on “Filter” then your pool filtration system is working just fine and you don’t have any issues.

But if the gauge reading is low, even on “Filter” setting it is possible that the multiport valve (MPV) is malfunctioning. Take it to a pool supplies store for a check, repairs or replacement if required.

4. Air in the System

Air getting into your pool’s filtration system can cause a drop in pressure and lead to low readings on the filter gauge. This can be caused by a number of factors, such as a loose pump lid or a cracked O-ring. 

When air enters the system, it creates bubbles that can disrupt the flow of water and cause the pump to lose prime. You are likely to hear a gurgling sound when this happens.

Another reason for air getting into the system is a suction leak caused by a crack or some other damage to the suction side of the plumbing line.

Sometimes, it could be as simple as low water level in the pool, causing air to be drawn through the skimmers.

The first step is of course to identify the actual reason and the spot from where the air is getting into the filtration system. Sometimes, you may get lucky and be able to identify the source immediately.

At other times you may need to conduct a more thorough inspection with help from a professional pool technician with specialized skills and tools to identify and fix the leak.

5. Pool Pump Has Lost Prime

A pool pump can lose prime and when that happens you will notice the pool filter pressure gauge reading 0. The reason is simple: a pump that has lost prime is no longer sucking any water and pushing it through the pool filter.

A pool pump may lose prime due to air leaks, clogged impellers, or a low water level in the pool. The solution is to identify the root cause of the problem and address it accordingly. 

Only after that can you  prime the pump manually to get it running again. Priming the pump manually requires you to turn off the pump, open the strainer basket lid, fill it with water, close the lid and turn on the pump.

Bottom Line

There can be a few other reasons for pool filter pressure gauge reading 0, but they are typically related to the 5 main reasons mentioned above.

Regular preventive maintenance, such as keeping the filtration system clean and lubricating seals and moving parts, is key to avoiding the above and other related problems. Moreover, make sure to properly winterize your pool before the cold season to prevent damage.

Thank you very much for reading the post. I do hope you found it informative and helpful.