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To backwash a pool sand filter, you’ll only need a few basic tools to help make the process smooth and effective. A backwash hose is an essential tool that keeps the backwash water from pooling up next to your pool.

Besides this, you’ll want to monitor your pressure gauge to know your average pressure. This is the best way to determine whether it’s time to clean your pool filter sand.

Keep reading if you want to learn all you need to know to keep your filter system running smoothly!

What is a Pool Sand Filter?

Sand filters are ubiquitous and are usually considered the best option for people with general pool knowledge. Pool sand is widely available at most pool shops, hardware stores, and most outdoor garden centers.

Ensure you buy suitable sand for your filter system and never use regular sand. Your pool sand filter likely uses one of two types of pool sand, which include:

  • Silica sand
  • Glass sand

These sands are similar to each other, but we don’t recommend interchanging them. Use the variety that is recommended by your filtration system’s user manual.

While similar, these two sand varieties have a few crucial distinctions. Glass sand medium is better for conserving water and supports the water filter system better than a silica filter.

However, silica sand, also called premium pool sand, is cheaper and more widely available. Both work well, but glass sand is a better option since it’s more efficient and effective for filtering debris from the water.

How Do You Properly Backwash a Sand Filter? 

Knowing how to backwash a sand filter is essential to regular pool maintenance. Follow these steps to backwash and rinse your pool filter sand properly:

  1. Turn off your pool filter
  2. Attach the backwash hose
  3. Turn your pool filter valve handle to backwash or waste
  4. Let the water flow for 30 seconds to 1 minute
  5. If the water flows unclear, continue backwashing until it comes out clear
  6. Turn off filter
  7. Switch the pool valve to rinse
  8. Let the rinsing process go for 30 seconds to 1 minute
  9. Turn off filter
  10. Turn the valve back to the filter setting
  11. Let the filter run for a few hours

Check your filter system’s PSI reading. One of the best ways to determine if your filter sand is cleaned is to check the pressure gauge. This will show you how much pressure is building up inside your system and indicate how hard your sand filter works to clean the water.

The harder the system works, the dirtier the pool water is. This indicates it’s time to clean the sand. You’ll know you’ve flushed out your pool sand filter when the PSI gauge indicates the pressure is back to normal operating filter pressure.

Why is it Important to Backwash a Sand Pool Filter? 

The backwashing process keeps your pool sand filter clean and free from contaminants. It also keeps your pool pump working efficiently and lessens the load on the pump to push water through the filter.

The more contaminants are in your sand filter, the harder your pump has to work to keep the water flowing. As long as the water flow is undisrupted, the sand can filter out contaminants and keep the water safe for swimming.

However, if you let the sand filter get too dirty, it won’t be able to clean the water anymore. The filter sand removes debris, bugs, and pollen from the water. When this debris is cleared out from your water, it keeps algae bloom and fungus from developing in your pool water.

How Do You Know When It’s Time to Backwash Your Pool Filter?

The PSI gauge is a good means of determining if you need to backwash your pool sand filter. If you need clarification on a regular pressure gauge reading, check the level next time you clean the filter. Or, check the user’s manual since some models have this pressure listed in the booklet.

Another way to determine if it’s time to clean your sand filter is to see how well your filter cleans the water. If you have a lot of algae bloom in your pool water or oils, there’s a good chance you need to backwash the sand pool filter.

Finally, if the water pressure from the pool jet is low, it could indicate your sand filter is dirty. However, this could also indicate your pool filter is clogged. If the backwashing process doesn’t improve water pressure, have a look at your pool plumbing.

How Long Do You Backwash a Pool Sand Filter?

You should backwash your sand filter for approximately 1-3 minutes. By this time, you should see the backwash hose releasing clear water rather than dirty water or cloudy water.

Some pool filters also have a sight glass that allows you to see how the water looks inside the system. If this water looks clear, then you should be done backwashing your filter system.


Sand filters are the most common pool pump and filter system. They’re the easiest to use and clean but are also the most energy-intensive and don’t collect as much debris as a DE filter.

If you live in an area with hard water, invest in a DE filter or replace the sand every 3-4 years. Pool filter sand is affordable and widely available, making it an ideal choice for any pool owner.

If you’re wondering which filter system is best for your needs, check out our article on DE, cartridge, and sand filter systems!