I love the design; it does not return many micro-bubbles to the sump and does not have any design problems that would lead to a collection of detritus inside the reaction chamber. Downsides: Like all in-sump skimmers, this skimmer requires a constant water level to perform correctly. I like my PM Bullet XL for stability because its a Beckett but it wont fit under my nano like this one does. I would like it if the collection cup were pre-drilled for an external waste collection container as that is necessary for extended trips out of town.