I’m still in the first stage candida diet and am taking chlorella. Just did a lot of reading on various sites and the only thing I noticed that could be “negative” is just a warning to NOT TAKE VITAMIN C WITH THE CHLORELLA. Chlorella already contains a lot of naturally-occurring vitamins and minerals, including B vitamins and Vitamin C! (I bought some Vitamin C since I was no longer able to eat any fruit but I suppose it will just sit in my cabinet unused, after all.)
Chlorella is a great super-food which will help eliminate more toxins as you cleanse. Just be sure to drink lots of water to help your body flush everything out.