I didn't spike it up to 5ppm ever. I feel that to be unnecessary with the goal of my bio-load. I set it to 1ppm let the bacteria adjust then doubled the second dose. It takes over twice as much now two get it to 1ppm, i'm assuming it eats it up instantaneously. I am shooting to rid 1ppm ammonia in 3-4 hours. It took about eight hours after 3 doses, it all depends on the bio goal of your particular tank. I have small fish and a large body of water in which any ammonia will be dispersed. Introduced a bacteria colony, cranked the temp. to 83, and put my fx5 and koralia 4 blowing straight up for all that oxygen. I also leave the light on 24 hours a day, I also feel this is helping. I use pure ammonia from a chemical company so there's none of that garbage in it. I'm also not done with my cycle, the fish won't be in for another week I would think. I assure you I'm being safe, I loves my fish.