Colleen, if it works, it works. You're committed to their method at this point, so you might as well try. Whether it will work depends on the details of your water, and on what exactly is in "Ultimate Metal Control by Suncoast Chemicals."

I don't know what's in it, and Pinchapenny has worked pretty hard to make sure I can't find out. So, your best bet, right now, is to follow their recommendations. If it fails, come back to us, and we can help you go another way.