Macro Aqua M-60 Hang-on External Protein Skimmer, 120 Gallon High quality protein skimmer for up to 120 gallon tank (depends on stocking) Big hang-on back filter; Water Flow: 320gph; Air Flow Rate: 80gph Effectively eliminates organic waste. Simply remove the collection cup to dispose tank waste Easy to install and operate Needle-to-wheel impeller - increases air to water contact