This product has been discussed by aquarists, debating the value versus risk to the tank. The Magic Eraser can be purchased at super markets and places like Walmart. I found a larger box one day and bought it to try out. I think this box cost around $5.50 and came with four sponges, for lack of a better word. About three months ago, I saw some chatter about the Magic Eraser on Facebook and how those people ...