There are a couple of factors that will make the B-S not work. One is if you have a tank that crashed & you added any kind of ammonia remover. The B-S needs ammonia to feed on. As far as cheaper methods of cycling a new tank, yes--adding some gravel & fishless cycling is the way to go. Unfortunately, a lot of folks don't have the patience or capability of understanding how this works. I have been around for a while now, answering a lot of questions by folks that have no comprehension about cycling. I don't think they are very interested in learning either. I think for those folks, my telling them to please put a bottle of B-S in their tank before adding fish (without any cycling, like they've always done) is best for the fish in the scheme of things. I also have found it extremely benificial for tanks I have that have crashed. Adding gravel from another tank would have done nothing to help my puffers gasping at the top of their tank, white as ghosts & puffed up. I did an 80% water change, added B-S & the tank was fine. It went from ammonia over 8 & nitrItes over 5 (the highest my tests will measure) to 0 for both in 24-48 hours. One of my tanks has crashed in this way 3 times. B-S saved my puffers every time. I really do swear by the stuff & would much rather recommend it to folks that insist on adding their fish to uncycled tanks. It happens way more than not!