When To Backwash Your Pool And How Often?

Last Updated on March 14, 2021

Maintaining a swimming pool can be challenging but it’s one of the most important tasks in keeping your pool clean and safe to swim on. Summer is the peak season for pool owners, but at the same time, this is the season where their pool maintenance routine is tested in terms of its effectiveness and efficiency. 

A pool not adequately maintained by owners is going to be a problem. Not only because of its cloudy appearance but also of the danger awaiting to happen. Like the fact that the swimmers might not be able to see the bottom of the pool and pool equipment can be damaged by an imbalance in your water chemistry.

To prevent this unwanted circumstance from occurring, as pool owners, you should know how to properly filter your pool water system, when to backwash your pool and how often to do it. 

In this guide, we will discuss everything you need to know about swimming pool backwashing and provide helpful insights to address your issue or concern about backwashing.

What is backwashing?

Backwashing is the process of cleaning your pool filter. As the name suggests, it reverses the water flow into the pool’s filter by lifting and flushing the filter medium (sand filter or diatomaceous earth filter). Afterward, the filtered residue will be drained into a waste line connected directly to a drain facility. 

Backwashing is a vital process in maintaining the cleanliness of your pool by keeping your pool filter clean. Because of how effective it is in keeping your pool water clean and clear, backwashing needs to be done regularly. How often should you need to do backwashing will be answered later in this post.

Why do you need to do backwashing?

This question is the most relevant one to address during peak season since keeping and maintaining your pool water’s cleanliness is necessary at all costs. On the contrary, there are three common indicators that you needed to take note of that will determine if and when it is required to do backwashing in your pool filter. The main signs or things to look for are the following:

  • Water Pressure – You should be able to do pressure reading and look for an increase in your PSI (per square inch). An increase in PSI might indicate that there is something wrong with your equipment. Either the filter is worked up due to a blockage or technical issue.
  • Water Flow – You need to be concerned about a selective reduction in water flow into your pool. This usually happens when something is restricting the standard flow of water into your filters, such as human natural waste or contaminants.
  • Water Clarity – If you noticed that the pool’s color is not clear and appears to be cloudy, this indicates that your filter is not properly functioning at all. Since it is unable to filter the dirt and debris from your pool.

How often should I backwash?

The most frequently asked question regarding efficient pool filtration we got from pool owners, “how often should I backwash my pool?“.

The answer heavily depends on your pool usage, your pool’s current location (if it is prone to natural dirt from its surroundings), and the type of filtration you use.

Some pool experts recommend that you should do backwashing at least once each week.

Another thing to consider is the starting level of the PSI. As a general rule of the thumb, you should do backwashing when the pressure gauge on your filter reaches 8-10 PSI at the starting level.

As I mentioned earlier, the frequency of backwashing your pool also depends on the installed filtration system you used.

Different pool filters used backwashing as a process to filter your pool water are: 

  • Sand Filter
  • Diatomaceous Earth Filter or DE Filter

What is a sand filter?

Sand filter uses natural sand as its filtering agent and traps any debris that passes through so only clean water is returned into your pool. This filter is considered the most straightforward filter to maintain and can last a long time without the need for any manual intervention. The usual frequency to clean a sand filter is every five years. 

When to backwash pool using a sand filter?

Upon taking everything into account, the sand in the sand filter should be replaced at least every five to seven years due to the sand’s gradual deterioration. This effect cannot be readily noticeable, but specific indicators will imply the sand’s inevitable deterioration.

These indicators can be seen in the pool water appearance. For instance, if your pool water appears to be murky than usual, if you have to increase your chemical consumption rate to keep your pool clean, and if you need to use your pool pump more frequently, chances are your filter’s sand needs to be replaced. 

Palmetto Poolfilter-50 Superior Pool Sand Filter – 20# Grade – Formula, One Size, 50Lb-A
  • Filtration – Our perfectly sized pool filter sand grabs insects, leaves, dirt, dust, sunscreen oil, hair and other small particles to keep your pool sparkling clean.
  • Pool Filter Sand – This pool filter sand is specifically designed to meet the standards for all brands of pool filters. We have upgraded our production with new robotics and screening technologies...
  • Sand - Our sand is 100% natural and has No chemicals added. This ensures smooth operation for backwashes of sand pool filters.
  • Clumping – Our sand will not solidify and not allow clogging and channeling of the sand in the filter. Our sand gives pool filter a smooth operation.

How to operate and backwash a sand pool filter system?

With a pool sand filter, backwashing is an easy process. Sand filters of all types and models use the same backwashing principle. So here is a simple guide on how to do backwashing using a sand filter.

  1. First, you have to turn off the pool pump.
  2. Set the configuration of your filter valve to “Backwash” and ensure it is locked in place.
  3. After that, turn on the pool pump and backwash until you can see the running water in the filter valve’s sight glass is clear already. (This may take approximately two minutes)
  4. Then, turn off the pool pump.
  5. Set the configuration of your filter valve to “Rinse” and ensure the handle is positioned in place. 
  6. After that, turn on the pool pump and rinse until you can see the running water in the filter valve’s sight glass is clear. This process is important because it brings back the sand to its optimal filtration position and prevents any residue from blowing back into the pool. (This may take approximately one minute)
  7. Finally, set the configuration to “Filter” and turn on the pool pump. 

What is a Diatomaceous Earth Filter or DE Filter?

Hayward W3DE6020 ProGrid D.E. Pool Filter, 60 Square Foot
  • The Hayward ProGrid 60-Square-Foot Pool Filter offers superior large-capacity performance, efficiency and water clarity
  • High-impact grid elements provide up-flow filtration and top-down backwashing for maximum efficiency
  • Durable, glass-reinforced copolymer construction ensures corrosion-free durability and withstand the elements
  • Heavy-duty, tamper-proof, one-piece clamp provides quick access to internal components without disturbing plumbing connections

This pool filter uses sedimentary rocks from fossilized remains of microscopic organisms called diatoms. These are often referred to as silica or silica deposits and are great for filtering water impurities because it’s very fine and can filter extremely small particles from your pool water.

Many pool owners believe a DE filter is better in filtering dirt and debris from your swimming pool. However, unlike sand filters, the DE filter always needs fresh DE powder added when you do backwashing.

Diatomaceous Earth Pool Filter, 25 lbs
  • Designed for use in above ground and in ground de filter systems
  • Leaves water sparkling and crystal clear without clumping
  • All-natural filtering media for de swimming pool filters
  • High-grade de filter powder can filter down to 3-5 microns

When to backwash pool using a DE filter?

DE filter reverses the flow of water inside a filler tank. Set by its mechanical purpose, this pool filter collects dirt. Eventually, the filter will be filled with accumulated dirt or debris resulting in low water flow to your pool.

If there is a low water flow, there is poor water circulation in your pool resulting in an algae problem in the pool area. Therefore, to prevent this from happening, you should do backwashing regularly to maintain your pool water’s cleanliness. 

Experts said that you should backwash your D.E. Filter once every 4 to 6 weeks of daily usage. But certain circumstances may occur that require backwash earlier than scheduled. 

  • If your filter runs continuously for 48 hours, you must do a backwash. Because D.E. will operate solely onto the filter grids, it can result in overpressure even if the filter grids remain clean. 
  • If by any chance, a tremendous amount of dirt enters the pool water, such as a fallen plant pot landed enters your pool, you must do a backwash.
  • If you got lucky for 7 consecutive days and got your pool area in total capacity, you must do a backwash since the amount of human waste such as sweat, hair, and oils might clog in your filter equipment.

Aside from these unwanted scenarios, you can just schedule your D.E. filter backwashing monthly.

How to operate and backwash a DE pool filter system?

The initial step-up to backwash using the D.E. filter is pretty much the same as the sand filter. The difference lies in an important aspect you need to have before backwashing: the D.E. powder. The D.E. powder is vital because you have to refill the filter with the new D.E. powder since the old one was washed out during the backwash process.

  1. Do the exact instructions provided in the sand filter operational guidelines, excluding the final step. (referring to Step 1-6 of the sand filter backwashing)
  2. You could repeat Steps 1-6 a few more times if you noticed that the filter remains slightly dirty after doing the basic cleaning mechanics, which are backwash and rinse.
  3. Turn the pump off when you are ensured that the filter is clean and select ‘Filter.’
  4. After that, you should carefully add the D.E. powder. In doing this step, you must relay and check the manufacturer’s instruction regarding the amount you should top up on the filter and add it to the filter. Typically, the amount will be about 80% of the entire load capacity of the filter. (Approximately 3-6 lbs.)
  5. Finally, turn on the pump while on ‘Filter‘ mode for a minimum of 30 minutes or more if a longer time is needed to the refilled D.E. powder to coat the entire filter grids.

Since you already know when it is necessary to do a backwash and how frequently you need to do a backwash. Let’s now discuss when backwashing is not required.

When is backwashing not needed?

To answer this, let me point out some pertaining details to imply that backwash is not advisable anymore to clean the pool filter.

  • When your pool area is located within a nearby construction site or is prone to runoff with flood during heavy rains. This circumstance stipulates that you might incur a tremendous volume of dirt. It is recommended to perform another cleaning strategy other than cleaning the filter.
  • Another impending scenario that will by-pass the filter is if your pool had developed an algae dilemma. This is because live algae can easily re-enter the pool by passing through a sand filter. Therefore, backwashing is no longer required, and it is recommended to just do vacuum cleaning of the pool. By vacuuming the pool entails that you should directly send the pool water into the drain. You can also use a good robotic pool cleaner to assist you in removing the algae from your swimming pool.

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