It's actually a media bag. After I change the gfo, it tends to go everywhere when I turn the pump on, so I put the bag there to keep it out of the rest of the sump. I don't remember the details about the pump but I'll look for them.Is that a filter sock on the outlet? Whats the gph for the pump that you are using for it? Its actually cheaper than i would have thought for something like that. Thanks for the suggestion.