Here's info directly from Seachem's forums and from one of their representatives. I posted this in another forum thread discussing Stability.
http://www.aquariacentral.com/forums/showpost.php?p=2443320&postcount=8
From SeaChem's site...
Stability® will rapidly and safely establish the aquarium biofilter in freshwater and marine systems.... Stability® is formulated specifically for the aquarium and contains a synergistic blend of aerobic, anaerobic, and facultative bacteria which facilitate the breakdown of waste organics, ammonia, nitrite and nitrate
Some, possibly all, of the nitrifying bacteria that complete the nitrogen cycle in saltwater are different than the bacteria needed in freshwater.
The nitrifying bacteria that we need to cycle a tank are strictly aerobic.
Neither the website nor their MSDS sheet specifically states that the product contains nitrosomonas, nitrospira and nitrosospira bacteria which are the three proven bacteria strains that perform the nitrogen cycle in freshwater.
From SeaChem's forums about their products and a "fishless cycle using Stability"
http://www.seachem.com/support/forums/archive/index.php/t-3748.html One of SeaChem's tech people replied
Your tank may not completely cycle in exactly 7 days. Some people may be able to cycle a tank in several days, while it takes others a week or maybe even a couple of weeks
This is proof that Stability does NOT instantly cycle a tank.
The only products that I know of that have the proper bacteria, based on Dr. Tim Hovenac's research, are his own products,
http://www.DrTimsAquatics.com which is based on his invention of Bio-Spira, only improved... and Tetra's SafeStart which is also based on Bio-Spira since Spectrum Brands bought out Marineland and co-owns the patent on Bio-Spira, along with Dr. Tim so they both have their own products... personally, I'd trust Dr. Tim's product over Tetra's but to each his own.
And now, Dr. Tim is actually actively posting here on AC in this thread... and others.
http://www.aquariacentral.com/forums/showthread.php?t=233550 Read through past the initial nay-sayers! ;-)