I haven't used any of them, but general consensus is Bio-Spira is the only product that really works.
And no. They are just to get your biological filtration colony started. Water changes won't affect it.
Karl
Why don't you just check out this nifty thread by Cheffi - members who are willing to donate filter material to help clone a tank or jump start a cycle. Perhaps (hopefully) there is someone in your area that could help outi want to now if u can buy stuff to speed up the cycle
has tetra got one?
True, but it is good to sometimes give some bacteria to your tank every now and then isn't it? Just to be on the safe side?