Yes, Metal Free is a sequestrant, but it is not one of the ones we recommend using. Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are far most effective. ProTeam's Metal Magic and Jack's Magic The Pink Stuff (regular), The Blue Stuff (fresh plaster), and The Purple Stuff (salt) are some of the top sequestrants. You can also find many other brands with similar active ingredients, some of which are noticeably less expensive.