We have 1 stock tank that holds 300+ gallons I think? and the other one holds like...50 or so I think. They are both poly- so they're a form of plastic- which is probably better than metal, but I don't think they make glass stock tanks! LOL The cows are out on pasture so they don't have mats to walk or lay on, BUT, I did make up a solution of CS water to spray on their hooves- with those pump sprayers. I also put Melaleuca oil and Eucalyptus oil in it which is also healing- I'm just hoping they don't hurt the properties of the CS!? We do have some cows with hairy hoof warts which the oils are supposed to help too, so.... I figured it would be good either way- if the CS doesn't have any effect because of the oils, then the oils will work instead. I guess we'll play it by ear. We have several cows that have mastitis which is why I'm curious about the CS in their water- we need to get rid of that soon, and it would be GREAT to be able to prevent it!!!!!!! AND, it would bring down the SCC (the bacterial count in the milk) Well, thanks for your response!