With the Fauna Marin multi-reference solution it is possible to test your water tests under real conditions. The solution is not made from freshwater, but the ion spectrum has been adjusted according to the test media, the salts and elements are in proportion and concentration similar to seawater. 

The 100 ml solution is stable and combines all these values in one solution (note: the values vary depending on the batch - the exact values are on the respective multi reference!):

Calcium 422 mg / l 
Magnesium 1315 mg / l 
Potassium / pottasium 409 mg / l 
Salinity 35 psu / 53.0 mS (25 ° C) 
dKH 6.6 / 2.35 meq / l 
Strontium 8 mg / l 
Nitrate 10 mg / l l 
PO4 0.2 mg / l
 

The measurement with the sterile reference solution is carried out normally. The measured value is compared with the reference solution and set in relation. This ratio is the correction value for the normal measurements with the aquarium water.