Open pond systems are generally regarded as a less than viable solution despite the advantages of being very cheap to run and more easily managed than other methods. The reason many people believe open pond algae farming isn’t is a good solution is the difficulty in finding a high lipid algae strain suitable for farming in a certain area that can cope with seasonal change and pH-swings. Another problem is that the algae will have to compete with invasive algae species and other aquatic organisms, including invasive bacteria, that make their way to the ponds.
There are two main types of open pond farming, the mono culture and the combined culture. Mono culture is when you only grow one species of algae in a pond. This method has been found to be sensitive to virus diseases and a single infection can wipe out an entire pond. Combined culture is when you farm several species.
It might seem odd that it is hard to find suitable hardy species of algae since algae seems to thrive everywhere. The truth is however that algae that produce a lot of lipids invest less energy into the production of proteins or carbohydrates and therefore tend to be a lot more sensitive than species with a lower oil content. An alga species that spends all of its energy on growth instead of diverting it to oil production tend to have a larger chance of surviving harsh conditions, unless of course those harsh conditions consist of a lack of nutrients in the environment.