The float place near me uses something like 1200 pounds of Epsom salt in a tank that is maybe twice the volume of my bathtub. Then they also regulate the temperature within the tank, both air and water, to be close to normal skin temperature. I’m not sure it’s practical.
If you want that sensory deprivation feeling, you have to control the air temperature as well and keep it in the dark, and it’s larger than a big tub. There is a company that makes a sensory deprivation float tent that will sell you all of the parts and salt. I looked into it a bit after enjoying my local float place. Maintaining the filters, the pH and dealing with the hundreds of pounds of salt seems like more trouble than it’s worth.