For determining the concentration of calcium and magnesium
Calcium (Ca 2 + ) and magnesium (Mg 2 + ), along with sodium, potassium, chloride and sulphate, are among the main natural components of seawater. organisms forming a calcareous skeleton, such as, for example, hard corals and red coral algae, magnesium and especially calcium are essential growth factors: indeed, these two elements constitute the main substance of the calcareous skeleton. In addition, many biochemical processes require magnesium and calcium. In saltwater aquariums, it is necessary to carry out regular monitoring of the decrease in the concentration of magnesium or calcium under the effect of cellular metabolism and the formation of skeletons. It may be necessary to add these two ions. In this way, it is possible to guarantee optimal, close-to-nature living conditions for all organisms and to avoid long-term damage.
In natural seawater, the calcium content is 400-410 mg/l while the magnesium content is 1280-1320 mg/l, i.e. a fixed ratio between the two of 1:3.25 . Due to the chemical and biochemical interactions between calcium and magnesium, efforts will also be made to obtain this concentration ratio in a seawater basin.
Advantages :
| • | Measuring range: Ca 300 – 498 mg/l |
| • | Measuring range: Mg 820 – 1800 mg/l |
| • | Accuracy: Ca 4 mg/l |
| • | Precision: Mg 20 mg/l |
| • | For the determination of the concentration of calcium and magnesium in seawater aquaria |
| • | Sufficient for about 50 applications |
Manual :
Note: First, the calcium concentration is determined, followed by the magnesium concentration with the same sample.
Calcium determination:
| 1. | Before use, shake the bottles well! |
| 2. | Rinse the glass bowl several times with tap water, then with aquarium water. |
| 3. | Using the dosing syringe, precisely pour 5ml of aquarium water into each glass bowl. Reserve one of the two cuvettes as a comparison sample. |
| 4. | Place a clean tip on the 1 ml dosing syringe with the red print and draw up reagent A until it reaches the 20 mark on the syringe (which corresponds to 0.5 ml). Total volume in the analysis sample. |
| 5. | Close the glass cuvette with the stopper and briefly shake the solution. |
| 6. | Then mix reagent B (powder) with the measuring spoon and pour a level measuring spoon of reagent B into the glass cuvette with the sample. Carefully swirl the cuvette until the powder is dissolved. The water sample takes on a light blue color. |
| 7. | Place another clean tip on the 1 mL dosing syringe with black print and draw up 1 mL of Reagent C. |
| 8. | Now add Reagent C from the syringe drop by drop into the water sample until the light blue solution loses all color*. After each drop, carefully swirl the cuvette. To better identify the color change, use the comparison sample (second cuvette prepared in point 3) and a white background and look from above into the cuvettes side by side. The drop by drop ends when the color change stops and it is no longer possible to distinguish the analysis sample from the comparison sample. |
| 9. | The remaining quantity of reagent C present in the syringe corresponds to the concentration of calcium C Ca in mg/l, indicated in Table I. Example: If the lower end of the syringe plunger is after the end of the titration at 0.46 ml, the remaining amount of reagent C is 0.46 ml. The calcium concentration of the sample corresponds to: Ca = 392 mg/l. |
| 10. | Reagent C left in the syringe can be returned to bottle C. |
Magnesium determination:
| 11. | Place the third clean tip on the 1 mL dosing syringe with green plunger and draw up 1 mL of Reagent D. |
| 12. | First add approx. 0.4 ml of reagent D to the water sample. The water sample again takes on a light blue color. |
| 13. | Now add the remaining Reagent D from the syringe drop by drop into the water sample until the light blue solution loses all color*. After each drop, carefully swirl the cuvette. To better identify the color change, use the comparison sample again (second cuvette prepared in point 3) and a white background and look from above into the cuvettes side by side. |
| 14. | The remaining quantity of reagent D present in the syringe corresponds to the concentration of magnesium C Mg in mg/l, indicated in Table II . Example: If the lower end of the syringe plunger is after the end of the titration at 0.35 ml, the remaining amount of reagent C is 0.35 ml. The magnesium concentration of the sample corresponds to: Mg = 1300 mg/l. |
| 15. | Reagent D left in the syringe can be poured back into bottle D. Rinse glass cuvettes, dosing syringes and syringe tips thoroughly with tap water and allow to dry until next use. |
| * Note: If the color change from light blue to colorless is difficult to spot, we recommend measuring with a bright light source, close to daylight. |
