An improved and more efficient design for an air driven algae filtration system is achieved because there are no moving parts other than an air pump, and the air is used twice. After using air to circulate water through a filtration unit, the air, still under pressure, is separated from the water. The air is then plumbed to other apparatuses or used for cooling. This allows the filter to be utilized using less electricity. The water is de-gassed before reaching the algae filter. Therefore, no splash guard is necessary to prevent water from splashing the lights. With no splash guard, lower wattage lights can be used to illuminate the algae. This also increases the efficiency of this system. This filter also lends itself to maintaining a reef aquarium.