if you are worried about aluminum, then your best bet is magnesium malate. This will chelate the aluminum. do a Google search 'aluminum + magnesium malate'.
the thiol bonds in the chlorella are what chelate the heavy metals, but they have no effect on aluminum.
If you are worried about mercury or lead then I highly recommend the cutler protocol
and be sure to stay away from all fluoride containing products if you are worried about Alzheimer's