What does filter-media replacement mean in practice?
Before backfilling, the old medium, sediment and water are removed, and then the distributors, central pipe and the inside of the cylinder are inspected.
When does it matter?
Replacing the hopper alone will not repair a cracked hopper or incorrect settings that may have caused a previous failure.
Which solutions are related to it?
The cause of wear is identified, the appropriate amount and bedding are applied, and the new bed is slowly watered and rinsed.