Magnesium Nitrate, Pure
CAS Number 13446-18-9
EC Number 233-826-7
Chemical formula MgN2O6 Mg(NO3)2
Solubility in water 712g/l (25 °C)
100g Mg(NO3)2 + 500ml water, 1ml of solution per 100 l of tank water yields a concentration of 1 ppm NO3 and 0.2 ppm Mg
50g Mg(NO3)2 + 500ml water, 1ml solution per 100 l of tank water yields a concentration of 0.5 ppm NO3 and 0.1 Mg
30g Mg(NO3)2 + 500ml water, 1ml solution per 100 l of tank water yields a concentration of 0.3 ppm NO3 and 0.05 Mg
The best practice is to add the recommended week’s worth dose of magnesium at once during water change.
In highly concentrated solutions, magnesium may react with phosphorus creating insoluble compounds.
50 Mg(NO3)2 should last for about 150 days (for a 100L aquarium)
Store in dark place, in room temperature.
Good To Know
Magnesium is a macroelement, it makes about 0.2% of a dry plant. Magnesium is a component of chlorophyll; it also activates many enzymes. Some sources classify magnesium as a mobile element (can transfer from one part of the plant to another), therefore symptoms of its deficiency occur in older leaves first. Plants absorb magnesium in the form of ions Mg(2+). In case of this element, its level is not as important as its proportion to calcium. The most commonly used source of magnesium is magnesium sulfate heptahydrate MgSO4x7H2O.
Interveinal chlorosis (sometimes in the form of spots) first occurs on tips and the edges of the leaves, then it spreads to the center of the blade; the leaves’ veins tend to remain green. With time the deficiency symptoms may also spread to younger leaves. Other sources suggest that deficiency symptoms most likely occur in upper and middle leaves. The areas affected by chlorosis may also change the colour from yellow to brown (or even lilac and red). In the case of more severe deficiencies, necrosis and leaves withering may occur. Sometimes leaves may start to fall event before other symptoms (e.g., change of colour) are noticeable. Some sources suggest that young leaves may become bent and their size may decrease.
Generally, the excess of magnesium is harmless. Some sources indicate that the excess of magnesium may lead to deficiencies or block of calcium and potassium.