The pool filter is essential equipment for the maintenance of your pool. And the cleaning of the sand filter is an essential step.
No need to change the sand too often. As long as it remains fluid and non-compact, you can keep it. Generally, changing the sand every 3 to 5 years.
It is necessary to also check the status of the sand and descale the filter. Limestone can be hung in the sand and grains form a kind of very hard concrete. To check the status of the sand, immerse the hand in the filter to catch the sand and make sure it flows between your fingers.
If the sand form hard clusters, change the sand and treat the water against the limestone...
Attention, if sand is more than a big block... There is more to change the filter!