What can happen if your backwash rate is too high?

Author: Kurt Howe MD  |  Last update: Wednesday, January 7, 2026

If backwash rates are too high, significantly more media could be lost— compromising filter performance. In any case, it is important to measure, track, and replace any missing media during your annual filter inspection and maintenance check.

What happens if you backwash too much?

Backwashing too often can reduce the filter's effectiveness. The sediment layer helps improve filtration by trapping finer particles. If you backwash before it's needed, you lose this beneficial layer, which can result in cloudy water.

What is the maximum allowable flow for backwash?

At ambient temperature, the recommended filter backwash rate is 6-8 gpm/ft² for anthracite and 13-15 gpm/ft² for sand. Anthracite filters associated with hot process softeners require a backwash rate of 12-15 gpm/ft² because the water is less dense at elevated operating temperatures.

What speed should I backwash my pool?

SCHEDULE A HIGHER-SPEED PUMPING TIME

This is an appropriate speed for backwashing and will clear out any air bubbles that can form in the pump and plumbing during the lower RPM period. For an average pool, set the speed to around 2,100 and 2,600 RPM.

Why is my psi still high after backwashing?

The filter will, most likely, increase in pressure over time (clean pressure - after backwashing) from residual dirt that's not removed during a standard backwash cycle.

POOL FILTER PRESSURE Too High Or Too Low? Troubleshooting Tips

What could happen if the backwash rate is too high?

If backwash rates are too high, significantly more media could be lost— compromising filter performance. In any case, it is important to measure, track, and replace any missing media during your annual filter inspection and maintenance check.

What happens if PSI is too high?

Driving with over-inflated tires can lead to several problems. The most problematic is a blowout, as they are more likely to occur with over-inflated tires. A tire blowout puts you and other drivers on the road in danger because it can cause you to lose control of your car.

What psi should you backwash?

Another industry standard is to backwash when your filter's pressure gauge reads 8-10 PSI (pounds per square inch) over the starting level or “clean” pressure. For example, if your filter is running normally at 15 PSI but increases to 25 PST, you should perform a backwash.

How many minutes should I backwash my pool?

Turn on the pump and allow the sand filter to backwash for 2-3 minutes or until the water in the sight glass (typically located on the top of the filter) is visibly clear. How long you backwash the sand filter for is not critical though you should visibly see clear water within 2-3 minutes.

What speed should a pool pump be at for vacuuming?

Medium – Switch to medium speed if you are backwashing or vacuuming the pool.

What is the required backwash rate?

The pump used for backwashing filters shall have sufficient capacity to provide a rate of at least 15 gallons per minute per square foot (10 L/s/m2 ... /s/m2) of filter area. The filter backwashing facilities shall be sufficient to backwash at the rate of 15 gallons per minute per square foot (10 L/s ...

How much water is lost during backwash?

Backwashing can take only a few minutes to complete, but for a typical pool, it consumes approximately 200 to 300 gallons of pool water! So, while your filter is losing unwanted dirt and debris—your pool is losing a ton of water.

What is the flow rate of backwash?

Additionally, the World Health Organization (WHO) recommends a backwash flow rate of 15-17 gpm/sf. Per Steve Andrews, the President of Nemato Corporation, a backwash rate should be determined by the filter bed expansion fluidization.

What happens if you forget to rinse after backwash?

Don't forget to rinse! Rinsing for 30 seconds after backwashing pushes the sand back in place clearing the filter of loose dirty water. If you don't rinse, you will have a puff of dirty water coming through the jet and back into your clean pool.

What psi is too high for a pool sand filter?

For most filters, 20 or 30 PSI is considered too high, but you should consult your pool professional to make sure that's true for your model. If you've cleaned the filter recently and you're still showing an above-normal PSI, check for leaks in your filter system.

Why is backwash bad?

Backwash is the term used for fluid which makes its way from a person's mouth back into a drinking container. Why is backwash considered bad? If you're sick, you could be putting sickness causing bacteria back into the container and if someone else drinks from it, they could get sick too.

What speed should I backwash my pool filter?

There is not an exact speed to use when backwashing the pool filter. Normally, it's something where you want to use one of the higher speeds to ensure plenty of water flow when doing this. I would say 2800 rpm is a good place to start and then you can adjust up or down as needed.

Is it normal to lose sand when backwashing?

If you have overfilled your sand filter during a recent sand change, it is not uncommon to experience a small amount of “blowback” into the pool after backwashing. You may also see some sand discharged from the backwash hose after backwashing.

What is the ideal level of chlorine in a swimming pool?

Regardless of how frequently or what system you use to add chlorine to the water, the chlorine level should stay between 1.0 and 3.0 parts per million (ppm) to maintain a healthy pool. Anything higher will make you run the risk of red eyes and swimmers itch.

What is the rate of backwash water?

If the manufacturer of the mineral you are using recommends backwash rate of 10 to 12 gpm per square foot, use the low range on cold water and the high range on warmer water.

What does strong backwash mean?

The swash is when a wave washes up onto the shoreline and the backwash is when the water from a wave retreats back into the sea. Destructive waves have stronger backwashes than swashes. This strong backwash pulls material away from the shoreline and into the sea resulting in erosion.

Can you over filter a pool?

Well, the answer is a definite yes. But for maximum efficiency and flexibility, we suggest that you go with a large filter and a variable speed pump so that not only would you be maximizing the filter's efficiency, but you'll have the option of running the pump at faster levels during heavy days.

What happens if your water PSI is too high?

Over time, high water pressure wears on your plumbing system and leads to: Leaking Pipes: High water pressure continuously puts too much force on your pipes. Eventually, your home's pipes will likely wear down until they can no longer hold back the water.

How much is too much over PSI?

While you should always stay within this range, you should also never be below 20 PSI, or over 50 PSI, or you risk serious tire damage (more so than with standard overinflated or underinflated tires to a lesser degree). Your car may have different ideal tire pressures for the front and rear axles.

Is 70 PSI too high?

How High Is Too High? The ideal water pressure level is between 50-70 PSI. If your water pressure goes above 70 PSI (even occasionally), you should install a pressure regulator to your main water line.

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