Procedure:

Use the eggshells with the inner membrane.
Place 2 liters of water in a pot and bring to the fire until it boils.
Place the shells in a mortar and try to grind them very well. Sand type or similar.
Once the water begins to boil, add the ground egg shells and cook for 5 minutes.
Also add about 15 grams or 1 tablespoon of epsom salt (very rich in magnesium).
Remove from heat and place the pot in a cool, dry place.
Cover the pot and let stand for 24 hours.
After this time you will proceed to strain the preparation and pour the strained water into a plastic bottle.
Do not throw away the residues that remain in the strainer, because they are used for plants, such as preventing snails or slugs from approaching.
With the water from the bottle you will proceed to water the plants at least once a month.
If you have leftover water in the bottle, you can store it in a shady place and use it again. Just keep in mind to shake it before using.