If you have no clue about how to use salt, then you definitely HAVENT been keeping fish, let alone rays for a long time. This is the FIRST thing you use to treat basically ANY sort of illness/injury. WE're talking about AQUARIUM/KOSHER salt, its different from the salt you use to make saltwaterr. MAKE SURE YOU PREMIX THE SALT IN WATER BEFORE YOU ADD TO TANK. IT WILL BURN YOUR RAYS IF IT DISSOLVES ON THEM. You add 1.5 pounds per 100 gallons once. Then the next day, do a water change, add back however much salt you took out PLUS MORE to make it 2-2.5 pounds per 100 gallons. Again the next day do another water change, and finally add enough salt to make your concentration 3 pounds per 100 gallons. So yes, if your tank is 300 gallons, then you add 9 pounds of aquarium salt in total, as simple as that. We didnt make any mistakes.