Today I went to a scrap metal business near me and decided to get 2 stainless steel plates instead of rods as there is more surface area than rods (I don't know if that makes a difference or not in the outcome). The plates are 2" wide and 9" and thin but not bendable. They cost me $1.50 for both of them. My son said they will not rust like the graters did. I work nights and have to go to work shortly and won't be able to use them until tomorrow.
As for the copper, I would imagine the professionals have tested different metals and found that the stainless steel would be the safest (no leaching perhaps). I'm only guessing.
I've added activated charcoal to my salt mix (a pinch) and the water still turns the same colors. I thought about using Epsom Salts too as they are suppose to help in detoxing. Haven't done it yet. I didn't know if it would effect the charger or not.
As for the feet position...how about tipping your feet to your heels (if water is deep enough and container is big enough)to allow more freedom for the toxins to come out? Just some thoughts.