Chemical control of pests and addition of nutrients. An outbreak of pests or infections in hydroponically grown crops can be quickly controlled by spraying the crops with appropriate pesticides or fungicides. Any nutritional deficiencies spotted in a crop can be rectified by adding the required fertilizer into the growing media. Any addition of chemicals to an aquaponic system entails careful consideration, as it can upset anyone of the different components such as fish, bacteria and worms. Iron deficiency can be usually tackled by supplementation, but pests have to be controlled mechanically.