Above ground sand filter question?

Question:Is it possible for a sand filter to loose it's sand into the pool?

We had replenished some of the sand this year, first time in 4yrs and it seems that it is realeasing back into the pool.

When I go to backwash and rinse, the little see through jar that is located on the filter has sand particulars in there.
We had a pool guy come out and fill the filter with sand, and he said that we really didn't loose much throughout the years.

I'm just wondering if anyone else has had this problem and how to resolve it.

Answers:
It is possible; the most common cause of this is damage to the laterals inside the filter. The laterals are spokes inside the filter that are supposed to hold the sand in the tank; sometimes they crack and let larger debris, and sand, through. (Some filters may not have laterals, but they will have something on the same idea that supposed to stop the sand but let the water through.) The only way to check for this is to open the filter, remove the sand, and check for damage.

Before you do this, are you seeing the filter sand in the pool? That is where it would be going if this kind of damage has happened.

Seeing a little sand in the sight glass (the industry term for it) is not uncommon when backwashing and not a big cause for concern (unless it is excessive amounts.)