🔁 Pool Filters That Require Backwashing

What It Is, When to Do It, and How to Get It Right

Proper filter maintenance is essential to keeping your pool water clear, clean, and safe. If you have a filter system that requires backwashing, following these steps ensures your pool filtration runs at peak performance all season long.

🧱 Types of Filters That Require Backwashing

The following filter types are designed to be backwashed:

1. Sand Filters

Use specially graded sand to trap debris
Common in residential pools for their simplicity and low cost
Require periodic backwashing to maintain efficiency

2. D.E. Grid Filters (Diatomaceous Earth)

Offer superior filtration (captures particles as small as 2–5 microns)
Use internal grids coated with D.E. powder
Must be backwashed and recharged with fresh D.E. after each cleaning

3. D.E. Quad Filters (Quad D.E.)

Important: These are often mistaken for cartridge filters but are NOT cartridge filters
Feature four internal elements, similar in appearance to cartridges, but operate with D.E. powder
Require backwashing and recharging with D.E., just like grid-style D.E. filters

❗ Note: Cartridge filters do not require backwashing and should be removed and hosed down when cleaning is needed.

💡 Why Do We Backwash Pool Filters?

Over time, as water flows through the filter in a single direction, dirt, oils, and fine debris accumulate in the filter media. This causes:

A rise in filter pressure
A drop in filtration efficiency
Reduced circulation and clarity

Backwashing reverses the water flow, flushing debris out through the waste line and restoring the filter to proper working order.

⏱️ When Should You Backwash?

You should backwash your sand or D.E. filter any time the pressure gauge reads 10 PSI above your clean filter pressure.

Not sure what your clean pressure is?

Backwash your filter as described below
Note the PSI reading after backwashing and rinsing — this is your "clean" baseline

📏 Pro Tip: Upgrade to a pressure gauge with adjustable indicators to easily track your clean vs. dirty pressure levels!

🔧 How to Backwash a Pool Filter (Step-by-Step)

🛠️ What You'll Need:

A backwash hose
Access to your filter's multiport valve

🌀 Backwashing Instructions:

Attach the backwash hose to the waste/backwash port
Turn the pump OFF
Set the multiport valve to Backwash
Turn the pump ON
Run for 3–5 minutes, or until water through the hose runs clear
Turn the pump OFF
Set the valve to Rinse, then turn the pump ON
Rinse for 30 seconds
Turn the pump OFF, set the valve back to Filter, and resume normal operation

📈 After Backwashing

Always record your new clean PSI immediately after rinsing and restarting the system
When your pressure gauge reads 10 PSI above that number, it’s time to backwash again

Keeping your filter system properly backwashed not only improves water clarity — it extends the life of your equipment and helps reduce strain on your pump and heater.

👉 📩 Have Questions? Contact Us »
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Watch these Helpful Videos from Swim University to see How to Backwash Your Filter!

Backwashing D.E. Filters