Pool filtration
When should you change the sand in a pool filter?
Filter media plays a central role in water clarity. Over time, sand can become clogged, form channels or lose effectiveness. This guide explains when to take action, which media to choose and how to maintain your filter to preserve effective filtration.
How does a sand filter work?
Water drawn in by your pool pump passes through the sand-filled filter. Each sand grain, with its jagged edges, acts like a mini particle trap. The water then comes out clean before returning to the pool.
But over time, natural erosion makes these grains smoother. As a result, they do not retain contaminants as effectively. Filtration then becomes inefficient, even if the filter still operates mechanically.
What to watch for
What signs indicate that it is time to replace the filter media?
The water remains cloudy despite good chemical balance and sufficient filtration time.
The pressure rises more quickly than before or does not return properly to its normal level after backwashing.
Backwashing does little to improve circulation or filtration quality.
Preferential pathways can form in the sand and reduce the surface area actually used to filter the water.
For silica sand, a lifespan of a few years is common, often around 3 to 5 years, but the actual condition of the media and filtration quality should guide your decision.
Types of sand for pool filters: which should you choose?
1. #20 silica sand
The most common and economical
Angular grains, good for trapping debris
Better micron filtration than regular glass
Lifespan of 3 to 5 years
Drawback: rapid clogging, which promotes bacterial growth
2. Recycled glass filter media
Made from 100% recycled glass
Electrostatic charge helps capture iron and manganese
Reduced channel formation
More eco-friendly, but slightly more expensive
Slightly less fine filtration than silica sand
Comparison
Silica sand or AFM® NG: which option should you choose?
The best choice depends on your budget, the level of filtration you want and your willingness to reduce maintenance in the long term.
Alternative to sand
AFM® NG: a higher-end filtration option
For owners who want to go beyond traditional sand, Dryden Aqua AFM® NG is an activated filter media designed to improve the performance of an existing sand filter.
It is installed as replacement media in a compatible filter without changing how the filter operates. To determine the amount needed for your model, it is best to check the filter capacity before purchasing.
Discover AFM® NG
How to change the sand in a pool filter: step by step
Materials needed:
New filter media (sand, glass, or AFM ng)
Screwdriver and wrenches
Garden hose
Wet/dry vacuum (optional)
O-ring lubricant
Steps:
Turn off the pump and close the valves
Drain the filter and remove the top cover
Remove the worn sand (with a shovel or wet/dry vacuum)
Clean the inside of the filter
Carefully pour in the new filter media
Close and lubricate the seals
Backwash for 2-3 minutes
Restore circulation and check the pressure
Tip: note the replacement date to track the maintenance cycle!
Backwashing: useful but not sufficient
Backwashing (backwash) temporarily reverses water circulation through the filter to flush out some of the debris accumulated in the media.
Rather than following a fixed schedule, primarily monitor the reference pressure of your clean filter and the return flow rate. Backwashing becomes appropriate when the pressure increases significantly or the flow rate decreases, following the manufacturer's recommendations.
Backwashing cleans the media, but it does not correct heavily worn, compacted, or severely channeled sand.
Annual maintenance: filter cleaner
Use a sand filter cleaner such as Rapid Action Filter Cleanse once per season. This product acts as a degreaser to remove:
Body oils
Sunscreens
Organic debris resistant to backwashing
Filter maintenance
The essentials for bringing your filtration up to standard
Three solutions depending on whether you are replacing the media, improving filtration, or maintaining the existing filter.
Classic option
Premium silica sand
The traditional choice for replacing the media in a sand filter at a controlled cost.
View the sand
Premium option
Dryden Aqua AFM® NG
An activated filter media for owners seeking a higher-performing and more durable solution.
View AFM® NG
Seasonal maintenance
Rapid Action Filter Cleanse
A cleaner designed to eliminate oils, grease, and deposits accumulated in the filter media.
View the cleanerFrequently asked questions
Changing the sand in a pool filter
How often should the sand be changed?
For silica sand, several years of use are common, often around 3 to 5 years. However, the actual frequency depends on maintenance, water quality, and the condition of the media.
Can sand be replaced with AFM® NG?
Yes, in many compatible sand filters. However, you must follow the required media quantity and the recommendations associated with the filter.
Should you backwash after changing the media?
After replacement, follow the procedure provided by the filter and selected media manufacturer before returning filtration to normal mode.
Does cloudy water always mean that the sand needs to be replaced?
No. Cloudy water can also result from a chemical imbalance, insufficient filtration time, a circulation problem, or an undersized filter.
Conclusion: replace your sand at the right time
Replacing the media at the right time
A filter in good condition may appear to be working normally even when its media has lost some of its effectiveness. Monitor water clarity, filter pressure, and flow quality rather than relying solely on the age of the sand.
If you are hesitating between silica sand and AFM® NG, the Piscine Hippocampe team can help you determine the quantity and media suitable for your filter.
