Do yourself a favor and examine the coils after so many treatments. I’ve done enough of those foot baths to actually see how rusted out the coils become after X amount of foot baths( I have my own machine+coils at home). I stopped doing them realizing that the rust was coming from the coils. All I know is I’m not going to soak my feet in a pool of rust. Ever notice that the rust has to be “scrubbed” from your feet and it “stains” pretty good. Sorry to say but sounds like rust to me. I don’t think that much brown gunk is going to be excreted(detoxed) from your feet–common sense. I’ve heard the black and green colors come from the paint(dye)on the coils. They are designed in a way to easily dissolve with salt+water. I could not believe how rusted out the coils looked after so many treatments..Pretty alarming.
Besides, Where and the heck would those kind of colors come from in your body???? What a bunch of quackery.