How to Backwash Pool Sand and DE Filters: Easy Step-by-Step Guide

Introduction: Keeping your pool water clean starts with a healthy filter. Learning how to backwash a pool filter is one of the easiest ways to keep your sand or DE filter working great all season long.  You can go here to learn some of the most common questions. 

Why Backwashing Your Pool Filter Matters

Your pool filter media works hard every day. It traps dirt, leaves, bugs, and tiny stuff you can't even see. Over time, all that junk builds up inside the filter. When this happens, water can't flow through as well. Your pump has to work harder. Your pool gets cloudy.

That's where pool filter backwashing comes in. Backwashing flushes dirty water out of your filter in reverse. This cleans out all the trapped gunk. It's like giving your filter a fresh start!

You'll know it's time to backwash when your pressure gauge shows 8-10 PSI higher than normal. Most pool owners need to backwash every 1-2 weeks during summer.

🏊 Pro Tip #1: Write down your filter's "clean" pressure reading. Stick it near your pump. This makes it easy to know when the pressure gets too high and it's time to backwash.

How to Backwash a Sand Filter: 6 Easy Steps

🏊 Pro Tip #2: Never skip the Rinse step! Rinsing prevents dirty water from flowing back into your pool when you restart normal filtering.

How to Backwash a DE Filter: 6 Easy Steps

DE filter backwashing follows the same basic steps as sand filters. However, DE filters use diatomaceous earth powder as the filtering material. You must add fresh DE powder after every backwash.

1. Turn off the pump. Always start with the pump completely off to protect your equipment.
2. Set the valve to Backwash. Move your multiport valve handle to the Backwash position.
3. Run the backwash cycle. Turn on the pump for 2-3 minutes until water in the sight glass looks clear.
4. Rinse the filter. Turn off pump, switch to Rinse, and run for about one minute.
5. Add fresh DE powder. Calculate the right amount for your filter size. Slowly add it through the skimmer with the pump running.
6. Test your water chemistry. Use a quality pool water test kit to check all levels and adjust as needed.

Special Tips for Saltwater Pool Owners

Saltwater pools need the same backwashing steps as regular chlorine pools. The main difference is what happens after. When you backwash a saltwater pool, you lose some salt along with the dirty water.

After backwashing your saltwater pool filter, always test your salt levels. You may need to add salt to keep your chlorine generator working properly. Most saltwater pools need salt levels between 2,700 and 3,400 PPM. A good test kit will measure salt along with other important chemicals.

Also check your chlorine cell every few months. Calcium can build up on the plates and reduce performance. Clean pool filter equipment lasts longer and works better.

🏊 Pro Tip #3: Keep a pool maintenance log. Write down when you backwash, what your pressure readings are, and any chemicals you add. This helps you spot problems early.

Frequently Asked Questions About Pool Filter Backwashing

Use a mask when adding your diatomaceous earth as it can be unhealthy if breathed in.  

How often should I backwash my pool filter?

Backwash your pool filter when the pressure gauge reads 8-10 PSI above your normal baseline. For most pools, this means every one to two weeks during swimming season. Pools with heavy use or lots of trees nearby may need more frequent filter cleaning.

How long should I run the backwash cycle?

Run your backwash cycle for 2-3 minutes. Watch the sight glass on your filter. When the water changes from cloudy to clear, the backwash is complete. Running too long wastes water and chemicals.

Do I need to add DE powder after backwashing?

Yes, always add fresh DE powder after backwashing a DE filter. The backwash process removes the old powder along with the dirt. Without new powder, your DE filter cannot trap particles properly.

Can I backwash a saltwater pool filter the same way?

Yes, the sand filter backwash and DE filter backwashing process is identical for saltwater pools. Just remember to test and adjust your salt levels afterward since backwashing removes some salt from your pool.

Why is my pool still cloudy after backwashing?

Cloudy water after backwashing usually means one of three things: your filter media needs replacing, your water chemistry is unbalanced, or your filter needs a deep clean. Start by testing your water with a reliable test kit to check chemical levels.

Keep Your Pool Filter Running Strong

Regular backwashing is one of the easiest ways to maintain a healthy pool. Whether you have a sand filter or DE filter, the process takes just a few minutes. Make it part of your weekly pool care routine.

Remember to watch your pressure gauge, test your water after every backwash, and keep good records. With proper pool filter maintenance, your equipment will last longer and your water will stay clean all season long.