Obviously the tanks are optimized for whatever it is they do (emulating senselessness?) but is it possible to emulate that?
How much epsom salt would you need and would it be cost-effective and safe to go down the drain relative to going out to an actual tank?
Please tell me it isn’t completely impractical and it could be done :)
You can do it on your floor if you take enough ketamine.
In all serious though, not really. I think other people already pointed out why.
However you can also learn to close the sense gates, without drugs or a bathtub. Later Jhana meditations do this.
And even just you relaxing in your bathtub with your ears under the water, that’s a step towards that stuff. The whole idea is to get very relaxed and minimize the stimulation from your senses, so that your mind can just relax and drift and be.
It doesn’t need to be full sensory deprivation to get the benefits in other words.