Why does Sand comes out of pool filter when backwashing?

Excessive pressure: If the pressure in the pool system is too high, it can cause the sand to be forced out of the filter during the backwashing process. This can happen if the pump is too powerful for the size of the pool, or if the filter is clogged.

Improper backwashing technique: If the pool filter is not properly backwashed, it can cause the sand to become stuck in the filter and eventually come out during the next backwashing cycle. To properly backwash a filter, the pump should be turned off, the backwash valve should be opened, and the pump should be turned on again for a period of time specified by the manufacturer.

Aged filter media: Over time, the sand in a pool filter can become old and worn, and it can begin to break down and come out of the filter during backwashing. This is more likely to happen with sand filters that are not properly maintained.

Cracked or broken laterals: The laterals in a pool filter are responsible for distributing water evenly throughout the filter. If the laterals become cracked or broken, it can cause the water to flow unevenly, which can lead to the sand being forced out of the filter during backwashing.

If you are experiencing sand coming out of your pool filter when backwashing, it is important to identify the cause of the problem and take steps to correct it. If the problem is not resolved, it can lead to damage to the filter and other components of the pool system.