I've sent an E-mail to my contact at Buckman Laboratories that makes PolyQuat. I'll let you know what they say but I suspect that the PolyQuat polymer, though long-chain and viscous, is not 5 microns in size and that's about the smallest that a DE filter can capture (I believe -- 10 microns is what usually is quoted for "typical"). I'll let you know what I find out.

Richard