Doughboy Filter Problem

[davey3229]

I have a 20 year old above ground Doughboy pool with a SilicaII sand filter. Filter does great job filtering small particles such as dead alge but light floating objects like small flies seem to get through skimmer filter and sand filter because I see them geting discharged back in to the pool from the filter return.
I backflush often for about 1 to 2 minutes until water stream is clear.
What else could be the problem?

[KevinH]

In your post, you did not mention if you had changed the sand in the sand filter, if it has not been changed within the past 2 years, it would be a good thing to do. It takes 130 lbs of #20 sand, available at your local pool supply store. It is easy to do, and takes about 1 1/2 to 2 hours to do.