I use only aquarium sea salt for my volcano shrimp (opae ula) tank.
I mix them with my home made distilled water.
Do not use common cooking salt such as Himalayan Salt, French Sea Salt or Portuguese Sea Salt.
It will kill the volcano shrimp (opae ula) instantly !
Trust me, it happened to me.
I am using Red Sea Aquarium Salt, you can use other brands as well.
Make sure it indicate aquarium sea salt for marine tank.