The JBL Iron Test-Set Fe is designed for the measurement and routine control of the iron content in saltwater and freshwater within the range 0.05-1.5 mg/litre (ppm).Why test? Iron is an indispensable trace element for plant and animal organisms. In addition to a sufficient supply of CO2 and other trace elements, iron is crucial for good plant growth and is consumed continuously. Glassy-yellowish colouring in leaf buds and young leaves is a sign of iron deficiency. Iron and some other trace elements are only stable in water for a limited time, even if they are bound to socalled chelators, as is usual in modern fertilisers. In addition any tap water added is usually iron-free. Therefore, the iron content needs to be monitored regularly with this test and replenished if necessary. Cncentrations as low as 0.1-0.2 mg/l are sufficient for good plant growth. In very densely planted aquariums, values of up to 0.6 mg/l can also be useful. In marine water, values of up to 0.05 mg/l are recommen