Why Your Pool May Have Low Filter Pressure

Glendale AZ Pool Maintenance

Swimming in your pool during the summer is one of the most enjoyable activities a family can experience. It’s hot out, and in Arizona, unless you’re going to the movies, up north, or out to eat, it’s not a lot of fun to be sitting in 110-degree heat. Swimming pools are a great way to stay home, relax, and enjoy each other’s company. Having friends and family over for BBQ’s while the kids swim is also a great time. While pools can provide memories and excitement, sometimes we forget how much work keeping up with pool maintenance can be! Get swimming pool maintenance, equipment installation, or upgrades in Glendale by contacting Pelican Bay Pools today!


Keeping Up With Your Pool Maintenance

You have to stay on top of your pools upkeep. There’s the water treatment and keeping it free from bacteria and the color crystal blue. You have to keep up with the skimmer and keep it free from all the debris, and sometimes even rodents, it might collect. An even bigger task is keeping up with the pool equipment and making sure your pump and filter pressure is efficient. What happens when you notice low pool filter pressure? How do you even know there’s a pressure issue? Let’s take a look at how to diagnose low filter pressure.

The pool filter pressure gauge is an often-overlooked device. It serves a very important function by letting you know the pressure inside of your filter tank, which in return translates to how well the entire filter system is operating. Most people don’t realize that different filter systems operate at different pressures. Your filter may be clean and normal at 9-10 psi, but your neighbor’s filter gauge could run higher, and be clean at 15-16 psi. Some systems with very low resistance can run very low pressures, barely registering, while other filter systems can run quite high, pushing 30 psi when the filter becomes dirty.

What’s The Correct Filter Pressure Gauge Read?

Most filter systems are designed to operate in the 5-15 psi or 10-20 psi range. The way to find out your particular correct pool filter pressure is to clean or backwash the filter thoroughly and empty the pump and skimmer baskets. Start up the filter, and when it reaches full head, or full steam, notice the pressure gauge reading. That is your clean, or starting pressure. It should never drop lower than that, and when it rises 5-10 psi above that starting pressure reading, it’s time to clean the filter again. The pool filter pressure should be steady, operating in a range of +/- 10 psi. When it’s outside this range, very low or very high, then you know that something’s wrong. Some gauges allow you to set the clean and dirty range, or you can write it on the filter tank with a marker.

When the Pool Pressure Gauge is Low!

When the pressure is lower than normal, this usually indicates a flow problem, and usually something is blocking or restricting water flow into the pool pump. It’s never a problem after the pool pump, because after the impeller, the pool water is under pressure, and obstructions result in higher than normal pressure. Here’s a list of common causes of low filter pressure.

  • Pool cleaner not moving around the pool well or may have stopped altogether
  • Reduced water movement in the pool
  • Pump not fully priming, or there’s air in the system when turned off
  • Clogged pump basket or skimmer baskets
  • Clogged pump impeller
  • Eyeball fittings not in place at pool returns
  • Filter valve allowing water to bypass filter
  • Air pulling into system at pump intake or pump lid, or valves
  • Closed or partially closed skimmer or main drain valves
  • Clogged skimmer pipes or main drain cover
  • Chemical treatments are good but water is still turning green or cloudy
  • Pressure normally 21 psi and goes to 6 psi quickly or overnight
  • Bad pressure gauge

Fix These Pool Issues So Everyone Can Swim Again

Skimmer and Strainer Baskets

If your skimmer basket is full of debris, you are effectively shutting off the pipe between the skimmer and the pump. Generally this will reduce the flow of water to the pump. If the pump has less water entering it, it is moving less water out. This means the pump is doing less work that in turn will reduce water pressure. Clean the debris out of the skimmer basket.

If your strainer basket is clogged, it’s very similar to the clogged skimmer basket.

A clogged strainer basket means less water flow that leads to less water pressure out the returns. Remove any debris that may be in the strainer basket.

Clogged Filter

Again, if water can’t get through a clogged filter, you will have less water flowing out of the filter. Incidentally, this will increase the water pressure in the filter signaling that it is time to clean the filter.

Wash your cartridge filter. Periodically soak the filter overnight in a TSP solution to get the grease and gunk out of the folds. Grease is produced by suntan lotion, sebum and pine tree needles. Then soak the cartridge in a weak solution of muriatic acid (10:1) to get the minerals out of the folds. Use the TSP before the acid or the gunk will set up in the folds. For sand filters you will need to backwash as required. Change the sand every five to seven years. In between changes, if sand has caked on top, take one to two inches off at the top and replace it with new sand.

Clogged Impeller

This problem is often overlooked. If the impeller becomes clogged with debris, water can’t rotate out the sides of the impeller. This decreases suction which reduces water flow through the pump. Clean out the impeller.

Suction Leak

A suction leak in the suction side of the pump can cause a number of problems. If it’s large enough, too much air will be sucked into the system, and the pump will lose prime. If it’s smaller, air will be sucked in through the pump and start to collect at the top of the filter tank. After some time air pressure at the top of the tank will create enough back pressure to reduce the flow of water significantly. When the pump is shut off, this back pressure will cause the water in the suction pipe to surge back and sometimes create a column of water up through the skimmer. Find the suction leak and close it.

Clogged Pump Pipes

A clogged pipe from the skimmer, suction line or main drain reduces the amount of water to the pump which can reduce water flow to the pump and create low water pressure out the return lines. Push a stiff wire down the skimmer or suction ports to see if you have a clog near the entrance. If there are no clogs there, you may have to get a pool professional to come in to check your pool pipes.

Bad Pressure Gauge

Every now and then your pressure gauge may be faulty. Your apparent low pressure reading may be due to a faulty gauge. Replace the pressure gauge.

Contact Our Glendale Pool Specialists

If any of these low pressure symptoms apply to your pool please call our office and we’ll set up an appointment to diagnose the issue. Understanding the problem sooner rather than later will allow the Pelican Bay Pools team to effectively fix the issue and get your pool running efficiently again. Call 623-825-7004 today or reach out to us online.

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