Macro Aqua M-50 Mini Hang-on External Protein Skimmer, 60 Gallon High quality protein skimmer for up to 60 gallon tank (depends on stocking) Small hang-on back skimmer; Water Flow: 238gph Effectively eliminates organic waste. Simply remove the collection cup to dispose tank waste Easy to install and operate. No priming required Needle-to-wheel impeller - increases air to water contact