The early Greeks treated anemia by drinking water with a rusty sword in the container. The spray should be used at least once and not more than three times. Excess copper in the water can cause iron deficiency. This can occur after copper based sprays have been used to control fungus. A solution is to flush the system, empty nutrient water and flush media with clear water.
Chelates prevent phosphate precipitation of iron.
When iron is used by plant excess chalates in solution may bind with copper and zinc, reducing their availability in nutrient water. The amount of iron also depends upon the amount of manganese, potassium and other elements in tissue. There is an antagonism between iron and manganese. Adding iron to nutrient water or media Many minerals used to supply calcium and phosphorus contain iron. Ground limestone, oyster shell, and many forms of calcium phosphate contain 2000-5000 PPM iron.