Three 20% water changes equal a 48.8% water change because 0.8^3=0.512. When I first heard about EI, I futzed around doing smaller water changes once a week for a couple of weeks. Then I decided to try the 50% water changes. Unfortunately, my fish didn't seem too happy about them. Consequently, I now do three smaller water changes several hours apart overnight to accomplish the 50%. A large water change can be dangerous if you don't test the waters first. On the other hand, and I know this is too late, a large water change really is the best thing to do to quickly clear a tank. I agree with that.
Last edited by Savetheplants; 08-02-2016 at 11:59 PM.