Finely puree the melon and drain the juice through a strainer. Measure out 250 g of the juice, mix a third of it with the algin and add to the rest. Pass through a sieve and let stand at room temperature for 30 minutes. Dissolve the calcite in the water and use a syringe to drip the melon juice into the solution. Cook in it for 1 minute and rinse with mineral water.