Backwashing a pool filter rinses the sand or DE, removing excess oils and debris. If you don’t backwash a pool long enough, the filter will clog, and the PSI will skyrocket.
However, backwashing the pool too much can damage the filter and the pump. It can also drop the water level below the skimmer.
Because backwashing for too long or too short a time can both cause problems, it’s important to find that “Goldilocks” length of time for backwashing your pool.
You backwash a pool for two to three minutes or until the water runs clear from the backwash hose. Turn the valve to the backwash setting, then turn on the pump. The hose will pull all of the grime out of the filter, then you can turn off the pump and realign the valve to the circulation setting.
In this article, I’ll discuss how long you should backwash your swimming pool filter, what happens if you backwash it for too long (or not enough), and whether or not you need to add sand after backwashing. Let’s get started!
How Long Do You Run the Backwash on a Pool?
Backwashing a pool is an essential part of removing excess debris and maintaining the water’s clarity. I recommend backwashing your pool filter for up to three minutes, regardless of if you have a DE or sand filter.
Failure to backwash your pool often enough or long enough can damage the equipment.
Here’s a list of signs that you’ve backwashed the filter enough:
- The filter’s PSI drops between 10 to 15 PSI. Your pool filter has a pressure gauge that lets you know when there’s too much debris in it. It’s time to backwash the filter media once it goes above 20 to 25 PSI. Run the backwash valve until the gauge is back in its normal operating condition, then return it to the regular circulation setting.
- The water coming out of the backwash hose isn’t dirty, cloudy, or sandy. Your filter should push out clear water that looks like it came straight out of the pool. If the backwash hose is loaded with gunk, it means the filter isn’t backwashed enough. Remember to clean the backwash hose by running a garden hose through it to remove excess buildup.
- The pump’s flow drastically improves once the filter is backwashed properly. A clogged filter can prevent your pump from circulating water, so you know it’s good to go when the flow returns. It might start as a slow trickle from the backwash hose, but it should gradually increase to a strong stream.
These indicators will let you know when it’s time to stop backwashing the filter. If you have to backwash it for longer than a few minutes, it might be time to change the media or add more sand to the filter.
However, backwashing the pool too frequently or for too long can cause several issues. I’ll cover all of them in the following section.
Can You Backwash a Pool Too Much?
You can backwash a pool too much because it will drop the pool’s water levels, letting air bubbles into the plumbing. These air bubbles can cause the pump to overheat and the filter to cavitate.
It’s best to stop backwashing the pool once the water looks clear since it means there’s no more debris.
Backwashing a pool is bad for these reasons:
- Backwashing the pool too much will drop the water below the highest inlet, causing the pump to run dry. The pump will overheat, grind, and potentially trip the breaker. Always keep an eye on the water level before backwashing, and don’t shy away from topping it off beforehand.
- Too much backwashing can cause friction in the filter, which can break the internal components. The filter’s tank can buckle and damage the manifold, gaskets, and center pipe. These parts will leak copious amounts of sand into the pool and through the backwash hose.
- Excessive backwashing will damage the backwash hose, multiport valve, and sealing clip. These parts are designed to handle a lot of pressure for short periods of time. However, too much water flow will strip the metal clip and the rubber hose. It’s important to secure the hose with a durable clip to ensure it doesn’t fly off from the PSI.
Getting a strong, durable backwash hose is crucial. The filter’s hose needs to be long enough to reach wherever you want to dump the water, wide enough to wrap around the backwash valve, and thick enough to prevent rips and creases.
The Gorilla Swimming Pool Backwash Hose is a 50-foot hose made of the popular brand’s incredibly durable rubber.
These hoses come with clips, so you don’t have to buy them separately. They offer a one-year replacement warranty for all manufacturer defects. They’re also three times thicker than traditional blue backwash hoses.
Do You Lose Sand When Backwashing?
You can lose a little bit of sand when backwashing since the valve reverses the flow of water through the media.
However, you shouldn’t lose more than a few tablespoons of sand. If your backwash valve leaks a lot of sand through the hose, there’s likely a broken component in the filter.
While a little bit of sand might come out, keep an eye out for these issues:
- If the plumbing leaks, the sand could flow into the pump. Sand in the pump will clog the impeller, and the pump will make a grinding noise. Turn off the pump immediately if you hear this sound because it can strip the bearings and ruin the motor, impeller, and housing assembly.
- If there’s sand coming out of the backwash hose after the first minute of backwashing, it’s time to turn off the pump. Open the filter and look for loose connections to ensure the manifold and center pipe are aligned. They can loosen from the pump’s high PSI, which allows the sand to get into the plumbing and backwash hose.
When you’re done backwashing the filter, check if you need to add extra sand. Knowing how much sand to put in the filter will help you maintain adequate filtration.
Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he’s not writing for Temperature Master, he’s usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.