The sand should last for a long time in some cases years. If you see sand in your pool in probably means it is time to change or if the pool looks cloudy that could mean sand is soft (has lost sharp edges). if you take some in your hands and rub them together it should feel very coarse if not change it
sand
Sand blasting is not the answer to a good prep for a replaster job
You can get swimming pool filter sand or a number of other filter media that can be used instead of sand from most pool shops. You can also get sand from under above ground pools from a builders supply or nursery.
Fish, sand, weeds, ducks, rocks
In the instructions it says not to use sand or it voids the warranty
This desert Nation must import its ultra-special Filtration Sand from The United States.
You may have to check the seals in the multyport on top of the sand filter.
Sand is normally put under the pool liner to create a smoother surface.
You don't use sand to level the ground that the pool sits on. The sand is used on the inside of the pool, after the ground has been leveled by taking the highest point down to the lowest point after the grass has been removed. The manufacturer's usually recommend 2" of sand on the inside of the pool before the liner is installed. It sounds like you are installing a used pool, since you do not have instructions. Here is a link to some instructions that could possibly be used. http://www.royalswimmingpools.com/install.htm
Sand
Possibly a grain of sand or debris in the flow tube.