no, it probably just means someone went in the pool with dirty feet.
One reason that causes sand to accumulate at the bottom of your pool is a sand filter with a broken lateral or laterals. Notice where the sand is accumulating? Is their return outlets from the filter directly above the small piles of sand in your pool? That is a broken lateral. You can fix this problem by scooping out the sand in the filter and replacing the laterals at the bottom of the tank. I have been cleaning and repairing pools for a long time and it is my suggestion that you hire a professional for this job.
Unfortunately, no. If the sand isn't level when you put the pool on top of it, the bottom of the pool will stay uneven after it's filled. Sorry.
One of the lateral returns inside of your sand filter may have snapped. When that happens, it can send sand out of your returns. Have your local pool place repair your sand filter.
first of all there shouldn't be a lot of sand at the bottom of your pool. assuming you don't live on the ocean where sand could become air born the only thing that makes sense to me is that something went wrong when you backwashed your filter. to get rid of the sand vacuum the pool every day until it disappears
If you are getting sand coming into the pool and have a sand filter you may have to replace worn laterals in the sand filter.
Dead algae.
It is best to use a fairly clean sand, like washed river sand shy away from a loamy sand as used by bricklayers.
There should be a drain plug near the bottom of the filter. Open it and let drain. The sand will stay in.
You should be able to just vacuum it out with the hand vacuum . If it is an enormous amount of sand using a venturi system like that used for emptying sand filters may be a good idea, You could run the water and sand into a drum and let the drum overflow back into the pool leaving the sand on the bottom of the drum.
Can you remove the bottom drain shut off valve and still blow out a plug the bottom drain on your pool.
Well, all I knew to do was to rush to Home Dept & got some sand -- not pool sand, the coarser landscaping type, and packed as much in as possible.
It already is used as pool sand!