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Aquarium Supplies

Salifert Magnesium Test Kit Information

Magnesium Profi-Test Kit Magnesium Profi-Test
  • Magnesium is present in natural sea water in a fairly high concentration (1350 - 1500 mg/L) and is an essential element of chlorophyll which is necessary for photosynthesis. Without photosynthesis plants, algae and coral would not be able to survive.
  • Magnesium also helps to maintain the correct combination of calcium concentration and alkalinity as it slows down the formation of calcium carbonate which can absorb many important trace elements within the aquarium.
  • Maintaining a correct magnesium concentration is therefore very important and is indirectly responsible for fast coral and calcareous algae growth by making it possible to maintain correct calcium and alkalinity figures.
  • Magnesium is depleted by algae growth and also by the use of excessive kalkwasser or by going far beyond natural calcium, alkalinity and pH values.
  • The Salifert Magnesium Profi-Test is easy to use and accurate with measurements in steps of 30 mg/L.
  • Results are not affected by strontium and calcium interference.
  • Can be used for marine water only.
  • Calcium and strontium will not interfere when their total concentration is between 200 and 650 ppm. This is mostly the case.

Keep out of reach of children. Not for consumption.


1. Add with the 5 ml syringe 3 ml of water in the test vial.

2. Add 6 drops of Mg-1 and swirl gently for 30 seconds.

3. Add 1 spoon of Mg-2 powder (spoon inside) to test vial and swirl for 10 seconds.

4. Place the plastic tip firmly on the 1 ml syringe and draw into this Mg-3 reagent until the lower end of the black syringe part is at the 1.00 ml mark. Ensure that during this that the plastic tip is submersed in the Mg-3 reagent to avoid that air bubbles are withdrawn instead of liquid. An air layer between the liquid and the piston is normal.

This is air which was present between the end of the tip and the piston, this will not influence the result.

5. Start adding the Mg-3 reagent with the 1 ml syringe to the testvial until the color changes to gray or blue (whichever color is observed first). Do this drop wise and swirl after each drop for a second or two.

6. Hold the syringe with the tip facing upward and read the position of the upper end of the black scringe part. Each division corresponds to 0.01 ml. The magnesium concentration can be obtained from the table or by use of the following equation:

ppm Mg = (1 - reading in step 6) x 1500

Natural sea water has a magnesium concentration of approx. 1300 - 1500 ppm. The concentration varies with salinity.

Too low magnesium concentration makes maintaining correct calcium and alkalinity concentration difficult. Magnesium concentration can be increased with Salifert's magnesium.

Magnesium Table
Note: If you took 1.5 ml of water in step 1 then multiply the calcium values by 2!
Reading in ml's (step 6) Magnesium Concentration in ppm
0.00 1500
0.02 1470
0.04 1440
0.06 1410
0.08 1380
0.10 1350
0.12 1320
0.14 1290
0.16 1260
0.18 1230
0.20 1200
0.22 1170
0.24 1140
0.26 1110
0.28 1080
0.30 1050
0.32 1020
0.34 990
0.36 960
0.38 930
0.40 900
0.42 870
0.44 840
0.46 810
0.48 780
0.50 750
0.52 720
0.54 690
0.56 660
0.58 630
0.60 600
0.62 570
0.64 540
0.66 510
0.68 480
0.70 450
0.72 420
0.74 390
0.76 360
0.78 330
0.80 300
0.82 270
0.84 240
0.86 210
0.88 180
0.90 150
0.92 120
0.94 90
0.96 60
0.98 30

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