Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to mix saltwater for an aquarium [title] Buy a sea salt mix. [step] Fish supply stores offer two ways to get saltwater for your aquarium. One is by pre-made saltwater or getting a synthetic sea salt mix that you blend into the water.

Ending1: If you plan to mix your own saltwater, make sure you purchase the pre-made saltwater solution that you add to water that you supply. [substeps] Get a dry synthetic saltwater mix. Ending2: The second is by making several saltwater mixtures. [substeps] For saltwater, you will need to mix six parts water to one part salt mix. Ending3: The process is much simpler and the saltwater helps the water retain salt. Two examples of natural salt mixed into saltwater is : [substeps] Pre-modified corks made from animal products and salt mix mixed into your aquarium. Ending4: The other is by boiling the saltwater. [substeps] The only difference between the two is that when the saltwater is cooked it tends to go bad before it is drained.

Answer format: ending1/ending2/ending3/ending4