OASE CrystalSkim 600 Surface Skimmer for Freshwater and Marine Aquariums – Compact Internal Filter for Film Oil and Debris Removal, Quiet, Adjustable Flow, Shrimp-Safe, for Tanks up to 160 Gal / 600 LBrand: OASE Color: Grey Features: QUICKLY CLEARS SURFACE DEBRIS Removes biofilm, floating plant matter, and dust from the waters surface to improve water clarity and support healthy oxygen exchange. Designed for use in both freshwater and marine aquariums. IMPROVES WATER CIRCULATION In addition to surface skimming, the built in bottom outlet creates gentle flow in low circulation zones where debris tends to collect. This helps reduce dead spots and