The following is excerpted from the research and writings of Dr. Mark Edwards, one of the world’s foremost authorities on algae.
VERTICAL, ANGLED OR HORIZONTAL
Algae are solar collectors so the plants benefit from maximum exposure to the sun. Some angled green solar systems track the sun similar to photovoltaic solar collectors. Horizontal algaculture systems, typically tubular or plastic bags provide another variation in solar exposure. Several companies use plastic bags that are typically rectangular or oval. XL Industries applies irrigation technology to algal production and their XL Trough uses a specially designed tube laying system that rolls out 10 tubes in furrows. Their tubular system is simple and inexpensive.
RECTANGULAR OR TUBULAR
Different shapes provide different levels of solar exposure. A wide rectangle, similar to an aquarium, holds a lot of water but does not allow each alga cell to have sun exposure very often. Consequently, thin rectangular tanks, about three inches thick, tend to out produce tanks that are wider. Tubular tanks may be a few inches wider because they present more surface area around the circumference. However, tubes around 6 inches typically out produce tubes that are wider.