If you are new to the hobby, or about to buy an aquarium that you need to cycle, I hope you read this. As you can probably tell I am one happy aquarium owner. After doing everything wrong with my first tank, I am happy to say that my new 125 gallon tank cycled in 1 week using bio spira. I bought my first 55 gallon tank in January 2008, and never heard anything about cycling a tank until it was set up for a week with 4 fish in it and a high ammonia level. The battle cry of my LFS was change the water to lower the ammonia. Along the way I was also told to change my filter media which I now know was a big mistake. A few weeks into this I discovered this site, and finally learned that my tank needed to cycle. It was at this time I learned about Bio Spira. This product made a difference, but did not have the instant results due to it having to work harder. This tank finally cycled about a month later with 2 more packs of Bio Spira, and 2 fish deaths. With the second tank I set up the tank, and ran the tank for 2 days. Per my conversation with Marineland I added the Bio Spira, waited until the water was clear, and added my 9 fish. After a small ammonia, and nitrite spike (nothing toxic) my readings are now 0 for both, with no fish stress or loss. I felt compelled to write this because of the various results people get with Bio Spira. Although it is expensive I would recommend that if you learn about cycling after a week or so, and have fish in your tank you should use a double dose of this product. Like I said it is expensive, but I think that will do the trick for you. The biggest problem you will have is finding the product. I live in Cleveland, and know of only 1 place to buy this. If you can find it and add it at the same time as the fish it works wonders.