Sand when backwashing

[Kawagama4]

I have been backwashing a number of times trying to get the cloudy water under control. Recently my husband took over as I was away and only backwashed and filtered. No rinse. He was backwashing for about 5 minutes at a time every few days. When I came home I did a backwash and rinse and noticed about a cup worth of sand in the backwash water. Should I be concerned?
Still somewhat cloudy but I had a ton of debris this winter as I had the cover off till the spring...leaves and worms sucking up. Otherwise am balanced with chemicals and cl2 is high. Any suggestions?