If it's a Dolphin robotic cleaner like a Dolphin Dynamic, the bag is going to be far better than a Polaris bag. I had a Dolphin, now have a Blue Diamond, and their bags filter as well as a DE filter. In fact, a cleaning with one of them (or the equivalent AquaBot and Red Devil brands) is equal to a DE filter running for the same period. For them, the high end robotics, the cotton ball trick probably isn't going to work. I used it on my old Polaris and it DID help.

Carl