Just to extend what WaterMom said, until you kill the algae, you can't really tell if something's wrong with your DE filter. The problems of dealing with live algae using a DE filter are going to overshadow everything else.

If you had not used an algaecide, we'd just recommend that you add sufficient chlorine to kill the algae -- given that you may have mustard algae, that might be a LOT of chlorine. But you said the algaecide was "effective" which means there's a good chance it was copper based. That, in it's turn, means that adding sufficient chlorine to 'do the job' is likely cause the copper to stain your pool..

Anyhow . . . membership updated.