Watched it pretty close last night... so much air coming down the pipe that it's filling the bag with air and for the most part the carbon it sorta stuck to the top of the bag, half out of the water... Going to try moving it to the back of the overflow box I have running between the refuge and sump and run it more passively, but with about a 500gph thoughput and see if that works any better. At least there I don't have any air to contend with.