If you currently have amalgams/mercury fillings, is it recommended to take chlorella or will it pull heavy metal out of the fillings and dump too much into the blood stream? If recommended, what brand and dosage?

Yes, use chlorella.

It's a super rich food and has massive benefits including cellular longevity factors and provides the G.I. tract protection from Hg (mercury) that enters via food or leaches from Hg in dental fillings.

Dr. Dietrich Klinghardt pioneered the daily use of chlorella for people with Hg fillings and Hg concerns, and found that it affords protection and prevents absorption of Hg back into the body ... something good to help with bonding and removing free heavy metals, not allowing them to enter from the g.i. tract.
Dr. Hal Huggins also was a staunch advocate of chlorella use before, during and after amalgam removal.

The advice to not take chlorella is unfounded. It won't move it to the brain, and much of chlorella's benefits are not absorbed, but remain in the intestines taking heavy metals out of the body.  Nor will it pull Hg out of tissues and put it in the brain. (Just basing that opinion on both science and clinical experience via lab tests.) Chlorella and cilantro, etc. have chelating factors, and when a metal is chelated, it will not cross membranes, but instead arrive at the kidneys and gall bladder for removal.

The advice to wait until after fillings are removed is also unfounded, because the Hg is already in the body, with or without fillings.

High doses are therapeutic and can cause some distress and be too much, but 2-6 caps a day makes good sense for daily maintenance in a toxic world.

Some brands we recommend are:

Quantum Chlorella: http://www.gutthrivein5.com/PRL-chlorella

Chlorella Manna: http://www.gutthrivein5.com/HF-Chlorella-Manna