Pool cleaning

How to Diagnose Common Pool Filter Problems

Having a pool filter is an essential part of maintaining a clean and healthy swimming pool. However, like any other equipment, pool filters can also encounter problems that may affect their performance. In this guide, we will discuss some common pool filter problems and how to diagnose and fix them.

Types of Pool Filters

Before diving into the common problems, it’s important to know the three main types of pool filters: sand, cartridge, and diatomaceous earth (DE) filters.

Sand Filters: These are the most commonly used type of pool filter. They work by passing water through a bed of sand inside the tank, trapping debris and dirt particles as small as 20 microns.

Cartridge Filters: These filters use a pleated cartridge made of polyester or paper as the filtering medium. They are known for their superior filtration and require less maintenance compared to sand filters.

DE Filters: DE filters use diatomaceous earth, a porous powder made from fossilized remains of tiny marine organisms, as the filtering agent. This type of filter can trap particles as small as 3 microns, making it the most effective pool filter.

Common Pool Filter Problems

Low Water Flow

One of the most common pool filter problems is low water flow. If your pool seems cloudy or has debris floating in it even after running the filter for an extended period, then you may have a low water flow issue. This problem can be caused by a clogged pump basket or skimmer basket, a dirty filter, or a faulty pump.

High Pressure

High pressure in the pool filter is another common problem. This can be caused by either a dirty filter or a clogged impeller. If you notice an increase in pressure on your pool’s pressure gauge, it’s time to clean or replace your filter cartridge or backwash your sand filter.


Leaks are another common issue with pool filters. They can occur anywhere in the filtration system – at the tank, pump connections, valves, or even due to cracks in the plumbing lines. To locate and fix leaks, turn off the pump and carefully inspect all connections for any signs of water leakage.

Broken Parts

Over time, parts of your pool filter may wear out or break, such as the O-ring, pressure gauge, or air relief valve. These parts must be regularly checked and replaced if necessary to ensure proper functioning of your filter.

Cloudy Water

If your pool water is cloudy even after running the filter for a significant amount of time, then there could be an issue with your filtration system. It could be caused by a dirty filter, inadequate circulation, high pH levels, or algae growth.

Diagnosing Pool Filter Problems

When faced with any of the above problems, it’s essential to diagnose the root cause correctly before attempting to fix them. Here are some steps to help you diagnose common pool filter problems:

Check the pump: The first step is to make sure that the pump is running correctly. If it’s not, then check for any loose connections or a tripped circuit breaker.

Inspect the filter: Turn off the pump and check the filter for any visible signs of damage or clogging. If you have a sand filter, backwash it, and if you have a cartridge or DE filter, clean or replace the cartridge.

Check water chemistry: Sometimes pool filter problems can be caused by improper water chemistry. Test your pool’s pH levels and adjust them accordingly using chemicals.

Look for leaks: As mentioned earlier, leaks can cause various issues with your pool filter, so be sure to inspect all connections carefully.


Owning a swimming pool comes with its share of responsibilities, and keeping your pool filter in good working condition is one of them. By understanding the common pool filter problems and how to diagnose them, you can ensure that your pool stays clean and clear all summer long. Remember to perform regular maintenance on your filter, such as backwashing or cleaning the cartridge, to prevent any potential issues from arising. If you encounter a problem that you are unsure of how to fix, it’s best to consult a professional for assistance. With proper care and maintenance, your pool filter will continue to provide you with sparkling clean water year after year. Happy swimming!