I am looking to sell a Prizm protein skimmer which is sized for a smaller fish tank or aquarium, up to 55 gallons. This is a hang-on-tank design, and functions fully as one unit. It is clean and ready to go. Filter media can also be inserted into compartments. I'm asking for $50 or best offer. Thanks. Location: Watertown it's NOT ok to contact this poster with services or other commercial interests mass