In both freshwater and marine, if the concentration of Fe is too high, we recommend a partial water change.
In fresh water, if the concentration is low, add ELOS Advanced Formula 4. In salt water, if the concentration is low, add ELOS Elements 02.Iron, in the modern aquarium, is a very important element. Its  lack, as in excess, can put at risk the balance of the entire eco-system. In fresh water a lack of iron, makes the plants  turn yellow and decay rapidly. In sea water it is essential for symbiotic algae, vital to the survival of many species of invertebrates, for phytoplankton and of course for macro-algae.Unfortunately, iron, even as a chelate, remains available for a very short time, so its concentration should be periodically verified to ensure that its level is maintained between 0.1-0.5 mg/l (ppm) in fresh water and 0.002-0.05 mg/l in seawater. Supplied with two Colour comparator cards. (fresh/saltwater)