I am conducting an experiment to see if type of liquids affect the apple discoloration. And I want every liquids I use to be equal. I am going to use green tea, lemon juice, vinegar, and salt water. Since I am adding water to salt and green tea mix, I thought that if I add extra water to vinegar and lemon juice, it would make the liquids to be equal.
As you want to determine which type of liquid affect the apple discoloration, you do not need to add water to vinegar and lemon juice because your experiment is qualitative not quantitative. You are basically trying to figure out if each type of selected liquid affects the apple concentration or not and not by how much each type of liquid affects the apple discoloration.