Originally Posted by Aztec Reef
are you talking about ls from a stablished tank or live sand that comes in a bag of water at lfs?
The bagged live sand is useless. You need sand from other live sand beds that are doing well or freshly harvested live sand from the ocean. The idea is to repopulate the diversity that slowly decreases over time. For most tanks once a year is enough. For smaller sand beds it needs to be done more often.
In my experience, aragonite sand in a DSB dissolves enough after a year that you can add several pounds of sand a year without increasing the depth of the sand bed.