Backwashing the sand filter system in your swimming pool is essential if the filter pressure is above 10 PSI (1 bar) and if the filter is clogged. With backwashing, the pool system continues to run free from malfunctions, and the pool water remains clean. To backwash a pool sand filter, the lever on the multivalve is set to backwash until the water in the system’s sight glass becomes clear. Finally, there is a short sand filter rinse, so the dirt does not end up in the pool.
Whether your sand filter system is from Intex, Deuba, or other brands doesn’t matter. The process is the same for all sand filter systems.
In this guide, you will find detailed instructions on how to backwash your sand filter system. You will also learn when backwashing is necessary, what to look out for, and how to avoid problems with backwashing.
What Does It Mean To Backwash A Sand Filter System?
Backwashing a sand filter system in a pool refers to the process of reversing the flow of water to clean out the accumulated dirt and debris in the filter medium, typically sand. This is essential for maintaining the filter’s effectiveness over time.
Regularly passing pool water through the filter traps contaminants, leading to a clogged medium, which impedes the filter’s efficiency. In a backwash, water flows backward through the filter to its waste or drain port, ejecting the debris from the filter medium.
While backwashing is necessary for sand and diatomaceous earth filters, it is not required for cartridge filters.
1. Switch Off The Pool Pump
For safety, the pool pump must be turned off before adjusting the sand filter system’s multivalve for backwashing. This precautionary step ensures that the adjustments can be made without the risk of injury or equipment damage.
2. Set The Lever To Backwash
The next step involves changing the setting of the sand filter system’s lever from the default ‘filter’ position to ‘backwash’, typically at a 06:00 position. This action reverses the water flow for cleaning the sand in the filter. It’s advised to attach a long wastewater hose to the filter system’s drainage valve to redirect the dirty water appropriately.
3. Switch The Pool Pump On Again
Once the lever on the multivalve is set correctly, the pool pump can be restarted. Monitoring the water’s clarity through the sight glass on the multivalve is crucial during this stage. The backwashing continues until the water in the sight glass appears clear, indicating a clean filter.
4. Rinsing The Pool Filter System
After backwashing, rinsing the filter system is critical to prevent dislodged dirt from re-entering the pool. This step involves setting the multivalve to a 10:00 o’clock position for rinsing and running the pump until the water in the sight glass is clear. The duration of this process varies, and it should not be rushed to ensure thorough cleaning.
5. Set The Multivalve To Filter Again
After completing the backwash and rinse, the pump is turned off again, and the multivalve lever is returned to the ‘filter’ position at 12:00 o’clock. This adjustment finalizes the backwashing process.
6. Return To Normal Operation
To resume normal operation, the pool pump’s operating switch is set to automatic mode, and the position of the multivalve lever is verified to ensure it points to ‘filters’. This concludes all necessary actions for maintaining the pool filter.
When Should You Backwash A Sand Pool Filter?
Backwashing a sand pool filter should not be a frequent activity, as occasional clogging can actually enhance filtration efficiency. However, it becomes necessary when the filter pressure rises 10 PSI (1 bar) above the normal running pressure or if there is a noticeable decrease in flow from the return jet.
Monitoring the pressure gauge is crucial for determining the right time to backwash. Additionally, if using flocculants or algicides like copper sulfate for pool maintenance, avoid backwashing your sand filter for 10 to 14 days to maintain chemical effectiveness.
After 3 to 5 years, if backwashing no longer effectively cleans the pool water, it may be time to replace the sand in the filter, as outlined in another blog post.
How Do You Know If Your Sand Filter Is Clogged?
The primary indicator of a clogged sand filter is a high-pressure display, typically in the red area of the gauge. This high pressure signifies that the filter is obstructed by debris. The following list outlines 4 indicators and causes of a clogged sand filter.
- Foliage and needle leaves: Leaves and needles that fall into the pool can enter the sand filter, causing blockages. Regular removal of these items from the pool can reduce the risk of clogging.
- Algae residues: Algae growth, especially problematic with black algae, contributes significantly to filter clogging. Filters capture algae particles during normal operation, leading to blockages over time.
- Calcification of the sand: Ineffective backwashing can result in calcified sand, which hinders the filter’s ability to function properly. This calcification blocks the normal flow of water through the sand.
- Colloidal substances: Substances like sweat, sunscreen, makeup, and others introduced by swimmers can gradually accumulate in the filter, leading to clogging. Encouraging swimmers to shower before pool use can mitigate this issue.
Installing a solar shower in the garden and encouraging its use can extend the time between necessary backwashes, thus preserving the sand’s condition and prolonging the filter’s lifespan. Employing a pool pump with a large filter basket can help prevent clogging by efficiently trapping leaves and larger impurities before they reach the sand filter.
By monitoring these indicators and taking proactive measures, you can effectively prevent and address clogging issues in your pool’s sand filter system. Regular pool maintenance is essential for the longevity and efficiency of the filtration system.
Why Do You Have To Backwash And Rinse The Sand Filter System?
The necessity of backwashing and rinsing a sand filter system arises from its primary function of trapping dirt and debris. A standard sand filter in private pools can filter particles up to 15 microns µ (0,015 mm). The use of a flocculant can enhance its efficiency by trapping finer dirt up to 10 µm (0,010 mm).
Initially, this trapped dirt aids in filtration, but over time, it leads to increased pressure in the filter, weakened return flow, and diminished filter performance. Consequently, pool water becomes cloudy. To prevent this and maintain clear water, it is crucial to periodically backwash and rinse the pool filter.
Is It Essential To Flush The Sand Filter System?
Flushing the sand filter system is critical for maintaining clean pool water. This process not only removes accumulated dirt but also reduces the pressure within the sand filter system. Regular flushing ensures the longevity and effectiveness of the filter system.
What To Do If The Backwashing Of The Sand Filter System Does Not Work?
In cases where backwashing is ineffective, the issue may be due to calcified sand. This can be verified by inspecting the sand manually. If calcification is confirmed, the filter sand must be replaced. To prevent future occurrences, it is advisable to consult resources about managing calcium levels in pool water.
What To Do If Sand Comes Out When The Sand Filter Is Backwashed?
If sand is observed in the pool during backwashing, it may indicate a broken line in the filter housing or an overly tightened inlet pipe during assembly. These components need to be replaced to ensure the proper functioning of the system. Fortunately, most parts of the filter system are individually replaceable.
Where Do You Drain The Water From Your Pool?
When draining water from your pool, small quantities can be safely discharged into your own garden. However, if the water contains additives such as antifreeze or copper sulfate-based agents, it should not be used for watering plants. It is imperative to avoid draining pool water into local water bodies.
How Are Other Filter Systems Backwashed?
Different types of pool filter systems have unique backwashing processes. The 3 main pool filter systems and a short guide on how to backwash them are listed below.
- Cartridge Filter: Involves removing the cartridge and rinsing it with water from a garden hose. Special cleaning agents are sometimes necessary to remove fats and oils.
- Multi-Layer Filter System: Combines sand and activated carbon for filtration. The backwashing process is similar to that of sand filters, but it requires replenishing the activated carbon post-backwash.
- D.E. Filter (Diatomaceous Earth Filter): Uses D.E. earth, which is cleaned through backwashing. Backwashing a D.E. filter often leads to the loss of some DE earth, necessitating its replacement. Moreover, the DE filter’s grid may accumulate grease and oils, requiring manual cleaning to prevent clogging.
Each filter type demands specific maintenance practices to ensure efficient operation and longevity. Regular and proper pool filter cleaning is key to maintaining clear and healthy pool water.
We recommend our blog and the search function for further guides about pool maintenance. If you have any questions about pool care, don’t hesitate to reach out to us via social media. We’re happy to help.
