I recently setup a 55G brackish tank via fishless cycling. Everything looked good, so I thought, and I added 3 fi8 puffers. By the 2nd day, there was a high ammonia spike. So I did some water change which helped a little. So I bought the Marine BioSpira for $25 then added it to the tank with lots of doubt. It didn't make a huge difference for the first 12 hours but the by the 24th hour, the ammonia reading was at 0. So for the doubters, it really works.