The water used must be reverse osmosis or distilled water—never tap water, as it may contain toxic substances or components such as heavy metals or high levels of chlorine, which are harmful to jellyfish. Deionized or RO water can be purchased at most supermarkets or pet stores.
You will mix the appropriate amount of salt with the desired number of liters of water, following the manufacturer’s recommended dose—typically 30–32 grams per liter of water to reach a specific gravity of 1.022.
To start up the system, it’s best to prepare the mix outside the aquarium. If you’re setting up a new tank, it can be done directly in the aquarium. Let the mixture sit for at least 24 hours to dissolve completely. Stir occasionally for better dissolution or use an air pump.
After 24 hours, measure the salinity using a hydrometer, densimeter, or refractometer. Adjust by adding more salt or more deionized/distilled water if needed.
If you are just starting the tank:
Turn on the aquarium pump to finish mixing and help stabilize pH and oxygen levels.
For water changes, always prepare the artificial seawater in containers outside the aquarium. Add the required dose of salt to deionized water, stir to dissolve, and wait 24 hours before use.