Blooms don't form randomly, they form where excess phosphate and nitrogen accumulate. These are water soluble pollutants from agricultural and industrial sites

Blooms don't form randomly, they form where excess phosphate and nitrogen accumulate. These are water soluble pollutants from agricultural and industrial sites so they follow the flow of the water table. When these nutrients meet open water algae populations that are already present increase proportionally to the increase in nutrient levels. I agree that the business model hinges on the efficiency at which they can filter and remove water. The minimum concentration of algae per volume that they can profitably extract determines the areas available to harvest from. The article quotes one pair per 57 liters of water, which seems like the location they used must contain a pretty dense concentration of algae (>5 g/L of usable polymer).