Yeah, Chlorella is very good in chelating- it's so good, that a person should only really use it if they have no more metals in thier mouth- or it will also start pulling continual mercury from existing amalgams.
Also- though it does bind to mercury, it does tend to redistribute and spill some along the way--which is why Algin is often used along with it to spounge up any "spillage" . It doesnt mean Chlorella isnt effective. It is very effective none-theless.
If you use Algin along with Chlorella, it makes for a perfect chelating "Team"!