How long should I backwash my filter?

Author: Marty Parisian  |  Last update: Friday, December 12, 2025

After the hose fills with water, backwash your sand filter for 2 – 3 minutes or until water runs clear. Shut off pump motor and push T-handle back down into locked position. Turn pump back on and note lower pressure.

How do you know when backwash is done?

You'll see water flow through those the hose or equipment in the view glass. Wait for a few minutes until the water runs clear. Turn off the pump to cease the backwashing.

How long should a backwash take?

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.

Can you backwash a pool too long?

If you have standard DE filter with a rotor backwash valve or a push/pull type, it is unwise to use this to drain the pool down. Any backwashing longer than a couple of minutes can damage the grids inside the filter. So only use the backwash feature to backwash the filter and not to drain water out.

Should you always rinse after backwash?

You should always perform a rinse after a backwash before going back to the regular filtration setting. If you don't, any remaining junk released from the sand that is still in the tank gets pumped directly into your pool. The rinse flushes it out first.

How Often Should You BACKWASH A POOL FILTER?

Where does the water go when I backwash my pool?

To backwash via the waste line is to run your pool water back through the filter, but rather than circulating the water back into the pool, it is flushed out through the waste line. Whilst the backwashing process is flushing out the dirt and debris, so is it flushing out your water with it.

What happens if you don't backwash?

If left unchecked, this can lead to cloudy water, poor chemical distribution, and even strain on your pool equipment. By regularly monitoring your filter's pressure, you can maintain optimal filtration performance, prevent unnecessary strain on the pump, and keep your pool water clean.

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.

Why is my pool dirty after backwash?

Most of the dirty and other foreign particles that enter your pool's system will end up here. But the dirt that accumulates at the bottom of the pool does not go to the filter. Backwashing a filter will lead to your pool being dirty temporarily. For a clean pool, do not backwash your filter before vacuuming.

Why is my pool pressure high after backwash?

If the pressure gauge continues to read high after you've cleaned the filter, something isn't working right. Something is preventing water from flowing back into the pool after it passes through the pump. Check for any of these problems: The returns or return valves are closed, partially closed, or blocked.

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 to do after backwash?

Always rinse for 20-30 seconds after backwashing. If you have a cartridge filter, clean the cartridge daily depending on how clean and free of debris the pool is.

How do you calculate backwash time?

Backwash run times can be anywhere from 5–20 minutes with rates ranging from 8 to 25 gallons per minute per square foot of filter bed area, depending on the quality of the pre-filtered water. Filtration and backwash rates are calculated by dividing the flow rate through the filter by the surface area of the filter bed.

How often should I shock my pool?

Shocking your pool regularly will help to keep the water clean and free of contaminants. You should aim to shock your pool about once a week, with the additional shock after heavy use. Some tell-tale signs that your pool needs to be shocked are cloudy, foamy, green, or odourous water.

Do you lose sand when backwashing?

After filling a sand filter it is normal for the filter to expel excess sand during backwashing for a few times . If this continues you have a problem.

What is a safe level of chlorine in a pool?

Chlorine. Chlorine is added to the water to kill germs, but it does not work right away. If used properly, chlorine can kill most germs within a few minutes. CDC recommends pH 7.0–7.8 and a chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs.

What happens if you backwash too much?

Backwashing a sand filter too often could lead to cloudy water. Assuming that your pressure gauge is functioning properly, resist the urge to backwash a sand filter until it's climbed at least 5 psi higher than the clean pressure.

Should you vacuum a pool on backwash?

To begin vacuuming your pool:

If you do have this option, it is highly recommended that whenever you have algae, you will need to vacuum to waste. This option allows you to vacuum the algae up and send it out through the backwash line, avoiding getting algae into your filter sand.

Does backwashing remove algae?

Use a vacuum or backwash the pool to remove the dead algae. Apply a mustard algaecide following the label directions. Allow the water to circulate for 24 hours. Use a pool vacuum or backwash the pool again to remove the remaining dead algae.

Should you run your pool pump while swimming?

Since most people will be swimming during the daytime, get ahead of the bacteria and debris by running the pump while you have swimmers in the water. Save money running pump by operating during non-peak times. Pump again in the daytime because bacteria thrive in warmer, still water.

What is the lifespan of a pool filter?

On average, the lifespan of a pool filter ranges from 5 to 10 years, depending on factors such as the type of filter used and the level of maintenance it receives.

Is it okay to run a pool pump 24 hours a day?

As mentioned above, it's okay to run your pool pump whenever it works for you, so long as it is running long enough to turnover at least once during a 24-hour period.

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.

Why does my pool get cloudy after I backwash?

You should backwash most sand filters every 2 weeks during winter and every week during summer. This also applies to cartridge filters as well. However, backwashing more frequently than this can lead to excessive sand loss, cloudy water, and poor filtration.

Should I backwash after shocking the pool?

If you're dealing with an algae infestation, brush the pool after shocking to remove lingering debris and run the filter. Rinse or backwash your filter to avoid recontamination. If you've still got traces of algae, shock your pool again.

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