s the name indicates the open-pond photobioreactor is simply an open body of water exposed to the elements. This may be an attractive route if you already have a pond in your yard. Be aware that different algae strains require certain conditions to grow. With an open-pond you'll need to think about a few key factors.
First, algae grows so thick in many cases that light will only penetrate about 3 to 4 inches under the surface of the pond water [1]. To maximize the amount of algae grown, many open-pond users create some sort of agitation to stir the algae around exposing more algae to sunlight. As seen in the picture below (these pictures are large examples of an open-pond, you wouldn't have to have a pond nearly this large to cultivate algae), the pond is in a race-track shape with a stirring device mixing the water. Algae will not grow quickly at night so the agitation device would not need to run 24 hours a day