I get asked this a lot and I would have to say yes and no. Good quality Chlorella is good for you and bad quality Chlorella is not good for you.
It all depends on how it is produced and what additives the manufacturer includes when making chlorella tablets. This is why I stress that you should not just look for cheap product. High quality broken cell Chlorella has a higher cost involved in production because of the technology involved.
A good manufacturer grows Chlorella in a very clean, unpolluted environment. They grow it in tanks rather than harvesting from the natural waterways because it is much easier to develop a superior product that way. Let's face it, the environment is polluted just about everywhere these days and there is more chance of the Chlorella being infected with E. coli or some other bacteria that thrive in polluted water.
Now the other point is how the manufacturer creates their tablets. Some use all kinds of fillers and binders to make the tablet. This should be shown on the label. Some high quality producers compress chlorella into tablets just using 100% pure powder. You really need to check the label and see if there are any additives. Many of these additives are just junk that it would be better not to consume.
If you want a high quality chlorella that is 100% pure broken cell that doesn't use any additives then check out The Chlorella Fella. It's guaranteed to be free of any impurities and has very quality control standards.
I take chlorella powder and tablets every day and you should too. It will do wonders for your health.