From my research, there are no simple or reliable or accurate tests for mercury poisoning that is chronic. Mercury ends up in deep tissues, organs , and brain where you can't measure it easily.
I would suggest you read Amalgam Illness, by A.C. Hall. I would recommend taking DMSA and ALA every 4 hours for three days,rest 4 days, repeat. There is no better protocol, but quite a few that are worse.
Chlorella may contain mercury as it comes from the sea.
I just tried some Glucosamine (which is made froms shellfish) and it made me depressed and toxic.