Yesterday, I was able to build a BOG filter just above my pond. I currently only have about 600 gallons in the pond from winter, but I want to keep it clean while I wait for monsoon season. The filter is simply a roughly 20-gallon, lined hole with a hose run to the bottom from a 12v pump. The hose is buried in rock, plant fabric, and more rock. This forces the water pumped up to the BOG filter to rise up through the substrate, which creates a large oxygenated surface area that is ideal for bacteria growth. Algae is nitrogen hungry, and bacteria eats nitrogen, making it difficult for algae to grow. The filtered water cascades back down into the pond. From the research I have done, BOG filters are ideal for solar powered applications because they are easy to build and require less energy to be efficient.
