Pool Filter Pressure Too High Or Too Low

Filter Pressure Too High main photo
Filter Pressure Too High main photo

Pool Filter Pressure Too High Or Too Low: Your pool filter pressure gauge is one of the most valuable pieces of equipment.

Just like a check engine light, it can alert you to potential problems with your filter system before things get out of hand.

But how do you know if your pool filter pressure is too low or too high?

And if there is a problem, how do you fix it?

Well, here’s everything you need to know about pool filter pressure.

Let’s dive in.

It’s totally free and will help you keep your pool clean and clear all season long.

So first, how does your pool filter pressure work?

Your pool filter needs a certain amount of pressure inside the tank to function.

This pressure is measured in pounds per square inch or PSI.

When water is flowing through normally, the filter pressure is normal, and your pool filter pressure gauge allows you to monitor this.

Your pool filter pressure gauge is attached to the top of your filter.

It’s a small dial with numbers and an indicator hand that moves up or down whether the pressure level is too low, too high, or just right.

When your water flows increase or decrease, the pressure inside the filter and the reading on your filter gauge will change.

If that pressure gets too low or too high, the filter won’t work properly, and that can damage your pool equipment.

So what is normal pool filter pressure?

Average filter pressure can range from 10 to 25 PSI.

What’s normal for your filter will depend on a few factors like filter size, pump size, power, and how clean or dirty the filter is.

But you can set a baseline number for what’s normal for your filter.

Right after you clean or backwash your filter, take note of the PSI reading on your pool filter pressure gauge.

That’s your normal pressure level.

You may even wanna mark this on the gauge itself.

Pool Filter Pressure Too High

Then check your pressure gauge once a week as part of your regular pool maintenance routine.

Now, there’s a chance that your pressure gauge is faulty or has worn out over time.

And if you turn the pump motor off and the pressure gauge doesn’t drop, that might mean it’s time to replace it.

Luckily, it’s not that expensive.

Another good indicator of normal water pressure is the flow out of your return jets.

If your water flow is fine but your pressure gauge is off, that might be another sign that your gauge is faulty.

So what happens if your pool filter pressure is too high?

When your pool filter pressure gauge starts to read higher than normal, it’s not necessarily a bad thing.

As your filter gets dirty, the PSI will naturally start to rise.

But as weird as it sounds, your filter is actually a little more effective when it’s a bit dirty.

Those particles of dirt and debris start to build up, it can help grab even more dirty particles as they pass through your filter media.

So a slight rise above normal pool filter pressure is okay, especially if your water flow is good.

But when the pressure reads 10 PSI above normal, it’s time to take action.

Usually, this means cleaning your cartridge filters or back washing your sand or DE filter.

And if you want a step-by-step guide on how to do this, be sure to check out our other videos on how to clean your pool filters.

If cleaning or backwashing the filter doesn’t bring the pressure level down, or the pressure rises rapidly after you’ve cleaned it, it may be time to replace your cartridges or grid.

Another way to fix high pool filter pressure, your pool air relief valve.

Air in your pool circulation system can cause high pressure.

This could happen if your pool’s water level is too low and it’s sucking in the air.

Remember, your water level should be right about the midpoint of your skimmer.

Air can also get into the system if you turn the pool off and then on again, say for vacation or to clean it.

When water begins to flow through the system, it pushes any air back up through the system.

Left too long, air can damage your equipment, especially the pump, which must contain water to function properly.

So that’s where the air relief valve can help manually release air from the system and bring the pressure back down.

This valve is usually a tiny handle near the filter pressure gauge or the top of your filter.

So what happens if your pool filter pressure is too low?

If the pool filter pressure gauge starts to read five PSI or lower than normal, it means your water isn’t reaching the filter quickly enough.

The most common cause is a blockage located somewhere before the filter.

This means it’s time to check the skimmers, pump basket, pump impeller, and drain covers for anything blocking your circulation.

So number one, check your skimmers.

Again, your pool water levels should reach halfway up the skimmer.

And make sure that the skimmer basket is seated properly to ensure good water suction.and make sure that your skimmer
flat door, aka the weir, is moving freely.

Number two, check the pump lid and pump basket.

Turn off your pump filter system and take off your pump lid.

Make sure that the O-ring inside the lid is fitted properly, and that your lid isn’t cracked or damaged.

And then remove the pump basket and empty it if it’s full of debris.

Number three, check the pump impeller.

Your pump impeller sits behind the pump basket in the impeller housing.

And it’s the only moving part of your pump that propels water into your system at very high velocity.

That means if it’s clogged, your pressure might be low.

You can easily unclog it by using a screwdriver or even a wire hanger to check inside and make sure the impeller
is spinning freely.

Just make sure your system’s off before checking it.

Now, there’s a less common but more serious cause for low pool filter pressure.

And that’s a leak somewhere in your system, like the pool pump.

Examine the pump carefully for any signs of a leak.

If the pump is the problem, you can either repair it yourself, hire a professional to repair it or replace the pump entirely.

Just remember, if your filter is clean, there are no blockages in your system, and your pressure gauge still says something’s wrong, it might be a problem with the pressure gauge itself.


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