Iron, Fe 13% EDTA Chelated
It is worth mentioning that saturation of a solution of one salt will decrease the solubility of another salt added to the same solution.
4g Fe 13% EDTA + 500ml water, 1ml solution per 100 l of tank water yields a concentration of 0.01ppm Fe
20g Fe 13% EDTA + 500ml water, 1ml solution per 100 l of tank water yields a concentration of 0.052ppm Fe
50g Fe should last for about 250 days (for a 100L aquarium).
Good To Know
Iron is a microelement; a dry plant contains about 100 mg/kg of iron. This element is key for the process of chlorophyll synthesis. Iron is a component of some proteins and it plays a role in cellular respiration. When it comes to its mobility, iron is an intermediate element therefore symptoms of its deficiency occur in younger, but also sometimes in older, leaves first. Plants absorb iron in the form of ions Fe(2+) or Fe(3+). This element should be always provided in the chelated form, otherwise it will be precipitated from water in the form of insoluble oxides and hydroxides which are not absorbed by plants.
Optimal dose is highly dependable on the type of chelate used, water hardness and on the light intensity. All of these parameters may have an effect on iron chelate stability. Generally speaking, the higher the pH, GH and light intensity, the higher iron doses need to be. Some aquarians dose even up to 1ppm of Fe a week.
Iron deficiency is quite common. When it occurs, it impedes plants’ growth. Usually the first symptom is interveinal chlorosis of young leaves. The contrast between areas affected by chlorosis and green veins is very noticeable. In more deficient environment, even the veins are affected by chlorosis. Finally, the whole leaves become yellow or even white. Symptoms may be also visible on older leaves. The youngest leaves may show a general chlorosis and older may show interveinal chlorosis. The size of the leaves may also decrease. Necrosis occurs in very severe cases.
Generally, excess of iron is quite unlikely. If it occurs, the symptoms then are noticeable on leaves located in the middle and at the bottom of a plant. At the beginning, chlorotic (or brown) spots appear which with time increase in size and turn into necrosis. Other sources suggest that the colour of leaves becomes dark-green (also brown or lilac) and also growth of sprouts and roots may be impeded.