StreamMax Classic stream pumps promote a healthy environment for aquarium fish and plant life by creating water currents that mimic a natural environment. These currents create aeration which help eliminate anoxic (or low oxygen) dead zones in your aquarium. Providing proper surface aeration is extremely important for the survival of your aquarium environment. StreamMax Classic pumps make it easy to adjust the water flow rate based on the individual needs of your aquarium's plants and inhabitants. Plants thrive on a gentle flow pattern, compared to a high velocity or more vigorous flow for fish or other purposes. This quiet, compact pump can be discreetly placed anywhere in your aquarium and adjusted by 90° for easy positioning and for directing water flow. StreamMax Classic 4000 has a 635 gallons per hour min flow rate and 1060 gallons per hour max flow rate. Designed with German engineering and manufactured in Italy, this pump is protected with a 3 year warranty.