Bigted,as Gadge has pointed out, very good on steel and cast but will eat Aluminium and brass ect, the soda ash I will look into but I only used about $2 worth of baking soda and from what I have heard the water may get all gunged up but will last as long as you want to put up with it, I have also read that if you use Graphite or carbon for the sacraficial anodes the water stays clean.
