had to give a sample of water to the pet shop man before I got my next two and he said it was ok.
But about the stuff in bottles, im going to have to disagree with you there, seeing as a majority of my Biology degree is microbiology.
Google endospores and have a read
Well the hard facts are it doesnt work. Or should I say more specifically it doesnt do what it says it does - i.e "Cycle" your tank.
I challenge anyone to perform an instant cycle using this stuff in bottles (i.e you can use the stuff, populate your filter media and put fish in straight away with 0,0 ammonia and nitrite readings every 12 hrs). Fact is it doesnt work.
What happens, is it "kick starts" a cycle, however you can do this just by adding fish anyway (a fish-in cycle), or by using household ammonia, or even fish food (fish-out or fishless cycle) to start the culture.
So yes, it will start a cycle off, but it doesnt do what it is meant to do i.e cycle the tank (making it pretty pointless).