Preis MgSO4 7H2O 450g

The normal magnesium content is around 1.350 mg/litre. In order to increase the magnesium content you need Preis magnesium chloride hexahydrate and Preis magnesium sulphate heptahydrate for mixing the chloride and sulphate anions in the proportions required for achieving the correct chemical balance. The mole relationship must be converted to the equivalent weight relationship as salts are sold by weight.

You must now calculate how much salt you need for 1 g magnesium.

7.58 g Preis magnesium chloride hexahydrate
+ 0.95 g Preis magnesium sulphate heptahydrate
= 1 g MAGNESIUM

Example:
Aquarium contents 480 l, magnesium content 1270 mg/l
You are aiming for a magnesium content of 1350 mg/l
Calculate the shortfall: 1350 mg
Less 1270 mg
80 mg x 480 l = 38.4 g magnesium
38.4 g x 7.58 g magnesium chloride hexahydrate = 291 g
38.4 g x 0.95 g magnesium sulphate heptahydrate = 36.5 g

Please weigh the substances using letter or diet scales, dissolve them in water, and add them gradually to the aquarium over a period of several days.
Or
for 10 days add each day a 75 ml 5% solution. From the fifth day on measure every two days the magnesium content of the aquarium.

You can also prepare a 5 % stock solution as follows:

Dissolve
380 g MgCl magnesium chloride
48 g MgSO magnesium sulphate
in 700 ml water and then top up to 1000 ml.

You can also prepare a 2% solution:

Dissolve
150 g MgCl magnesium chloride
20 g MgSO magnesium sulphate
in 700 ml water and then top up to 1000 ml.