Abstract: A method for harvesting algae according to embodiments of the present invention includes filling a reservoir at least partially with a liquid, submerging a bag at least partially in the liquid, the bag containing media, the media comprising algae, the bag comprising a first end, a second end, a harvesting port located closer to the first end than to the second end, and a gas port, delivering gas into the bag through the gas port, and raising the second end of the bag by accumulating the gas at the second end to flow the media toward the harvesting port.