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hw Magnesium sulphate heptahydrate

from 15,54 


Pure Magnesium sulfate heptahydrate (MgSO4 x 7H2O) in fine crystalline form for the increasing of the Magnesium concentration in combination with hw®-Magnesiumchlorid-Hexahydrat.


(MgSO4 x 7H2O)

Magnesium sulfate heptahydrate in fine crystalline form, for the adaptation of water parameters. Addition according to the combined magnesium sulfate and magnesium chloride dosage.

The main concept:

Beside sodium chloride, magnesium is the second biggest component of the natural marine salt. But compared to sodium chloride, the magnesium level in the aquarium water will slowly declaim due to the adsorption of several marine organisms (like corals, mollusks and other reef building organisms) and bio-chemical processes. Therefore to avoid deficits in Magnesium the concentration of this element should be adjusted from time to time. In natural marine water the Magnesium concentration is around 1250 – 1380 mg/l and depends strongly from seasonal changes and geographic location.

To elevate specifically the Magnesium concentration in the aquarium water you will need hw®-Magnesiumchlorid-Hexahydrate and also a specified amount of hw®-Magnesiumsulfat-Heptahydrat, to not alter negatively the natural balance of the chloride- and sulfate ions in the your aquarium water.

Best practice:

The exact calculation of the needed quantities in gram has to be made by calculating with the molar mass and under consideration of the bounded crystal water together with the fixed relation of chloride to sulfate in natural marine water. By using the combination of hw®-Magnesiumchlorid-Hexahydrate and hw®-Magnesiumsulfat-Heptahydrat the weight relations are as following:

0,95 g             hw®-Magnesiumsulfat-Heptahydrat (MgSO4x7H2O)

7,58 g             hw®-Magnesiumchlorid-Hexahydrate (MgCl2*6H2O)

1,00 g            Magnesium (Mg)

Sample calculation:

A marine aquarium with 500 l water volume has a Magnesium concentration of 1200 mg/l, the concentration should be elevated to 1300 mg/l. To calculate the needed quantity of Mg in gram proceed as following:

1300 -1200 = 100 mg/l * 500 l (aquarium volume) = 50 g Mg in total
50 g x 0,95 g =   47,50 g hw®-Magnesiumsulfat-Heptahydrat (MgSO4x7H2O)
50 g x 7,58 g = 379,00 g hw®-Magnesiumchlorid-Hexahydrate (MgCl2*6H2O)

Both quantities should be solved together in around 600 ml RO-water (or demineralized water) and filled up to finally 1000ml.

From this solution should be added 100 ml daily over the next 10 days to the aquarium water. On the 5. day please realize a control measuring of the actual magnesium level/concentration in the aquarium water, so that eventually adaptation could be made.

Weight 5 kg
Gebindegröße u. Verpackungsform

500 g, 1.000 g, 5.000 g, 10kg, 20 kg, 25 kg

Company holidays

from July 12th, 2021 to August 2nd, 2021

During this time no dispatch, pick-up

or acceptance of goods is possible!