Bathtub Stains How To Remove Brown Stains From The Bathtub?

How to remove Brown stains from the bathtub? - bathtub stains

Last night I put some Clorox and Ajax in the bathtub with the intention of cleaning weeds and morning. Spots When I woke up this morning, it was all brown and not the tub washing seems to remove them. Suggestions on what is happening here and what can I do about it.