Regular backwashing is one of the easiest and most dependable methods to ensure consistently healthy pool water year-round, particularly during the summer months, while also maintaining a clean filtration system.

Understanding the timing for backwashing your filter is crucial for maintaining clean pool water and ensuring your filtration equipment operates at its best. Fortunately, there are three clear indicators that signal when it's time to backwash your pool filter. These include:
Pressure Increase:Â A rise in PSI (per square inch) indicates strain on your pool filter due to blockages or faulty equipment.
Flow Reduction:Â Debris and contaminants clogging the filter media restrict the water flow rate, reducing the amount of water entering your pool.
Water Clarity:Â Cloudy water often signals dirty filter media that is ineffective at capturing dirt and debris entering the pool.
How do I backwash my pool's sand filter?
Follow our comprehensive, step-by-step guide to backwash your sand filter:
1. Ensure the pool water level is sufficient, ideally about ¾ up the skimmer box.
2. Turn off the pump.
3. Disconnect the suction cleaner from the skimmer box, including the vacuum plate.
4. Empty the skimmer basket.
5. Your sand filter is equipped with a multi-port valve offering six settings: filter, rinse, closed, backwash, recirculate, and waste.
6. Confirm all valves in the backwash discharge lines are open.
7. Set the multi-port handle to the ‘backwash’ position and switch on the pump. You'll observe water flowing through the backwash line.
8. Run the backwash until the water in the sight glass runs clear, typically a few minutes, then switch off the pump.
9. Turn the multi-port handle to the ‘rinse’ position and run the pump for 30 seconds.
10. Turn off the pump.
11. Move the multi-port handle back to the ‘filter’ position. Ensure it is securely set.
12. Turn the pump back on. Water should resume flowing through the jets. Check for any leaks in the backwash line now that it's set to 'filter'.
13. Reconnect the vacuum plate and suction cleaner.
14. Refill the pool to the correct level and proceed to test and rebalance the water with appropriate pool chemicals.
All sand filters use the same basic mechanics: when set to ‘Filter’, water flows from the pool, through the filter, and back into the pool. The sand inside the filter system blocks debris, dirt, and oil. A typical sand filter multiport system has 6 different settings – ‘Filter’, ‘Backwash’, ‘Rinse’, ‘Circulate’, ‘Closed’, and ‘Waste’.
However, when you vacuum your pool, a concentrated level of dirt and debris get deposited into the sand – the result being that the sand becomes dirty and clogged with contaminants that, if left unchecked, will reduce the sand’s ability to filter and, ultimately, end up back in your pool, reduce the clarity of the pool water. Backwashing prevents this. Backwashing reverses the flow of water, lifts up and flushes the sand, and then expels the dirty water via a waste line into the ground or drain.
In order to prevent residual blow back into the pool, once you’ve finished backwashing it’s highly advisable to rinse the filter. Just as the backwash lifts and flushes the sand, the rinse resets the sand to its original position for optimum filtration.
If you want to read more about how to clean cartridge filters and DE filters, check out our recent blog!
How often should I backwash my pool filter?

Determining how often to backwash your pool filter depends on factors like pool usage, nearby trees and the leaves it may bring into the pool, and lawn maintenance habits that can introduce debris.
However, many pool owners opt to backwash weekly during the summer as part of routine maintenance, typically after vacuuming to clear remaining particles stirred up.
A dirty filter can promote algae growth and strain your pump by hindering water flow through clogged media. Green pools also pose safety concerns.
When should I avoid backwashing my pool?
If your pool has accumulated excessive dirt due to factors like nearby construction, prolonged neglect, or runoff from flooding, it may be necessary to bypass the filter entirely. In such cases, vacuuming directly to 'Waste' and draining the vacuumed water directly can be a more effective solution.
Important backwashing points to follow:

Always remember to turn off the pump before adjusting or resetting the filter valve setting to prevent potential damage or system failure.
Sand filter backwashing results in water wastage as water is expelled to waste.
To minimise water wastage, monitor the water quality in the sight glass closely.
Avoid excessive or unnecessarily prolonged backwashing sessions.
Sand filters operate most effectively during the middle of their filtration cycle.
Needing a hand? Call Pool Wizard!
At Pool Wizard, we prioritise the maintenance and care of your pool filtration system to ensure optimal performance year-round. Our commitment includes regular backwashing to keep your pool water clean and clear. If you ever need assistance with backwashing or any other aspect of pool maintenance, our dedicated team is ready to help. Pool Wizard is here to ensure your pool remains a refreshing oasis for you and your family to enjoy.
Simply fill out our contact form and we'll be in touch with you ASAP.