A key marketing feature of hydroponic systems is to be certified 100% organic. To obtain this certification one of the many restrictions is not using chemical fertilizers. Since, by definition, hydroponic systems do not contain any fish or other animals who’s waste products could serve as a source of nutrients for the plants grown in the system operators of hydroponic facilities must look at other external organic sources for nutrients. These external sources must then be mineralized using micro-organisms producing nutrients such as nitrogen (in the form on ammonia which is then oxidized to nitrate via nitrification) and phosphate in the form of soluble reactive phosphate (SRP) along with many micro-nutrients.
Successful mineralization depends on heterotrophic bacteria present in sufficient quantities operating either aerobically or anaerobically. Aerobic digestion depends on large amounts of aeration to maintain high oxygen levels and prevent the creation of foul odors and bulking of solids. Anaerobic mineralization is enticing as it can result in more stable water conditions (higher pH, increased alkalinity) but there is a greater chance of system failure due to the production of nitrite or hydrogen sulfide. The bacterial processes occurring in hydroponic systems are subject to many myths and misconceptions including the bacteria species responsible, how fast they may react to changing conditions and what conditions will promote which bacteria. A framework of basic knowledge regarding aquatic microorganisms in hydroponic systems will be presented along with methods for introducing and maintaining beneficial bacteria to the system. A better understanding of the microorganisms will allow operators to more efficiently manage their systems saving time, money and resources.