I've never used it, but from what I've HEARD, it's crap.
So, it'd be like.....buying a teeny bottle of water that'll do zilch and dumping it in.
you'd be better off setting it up new, and stealing some filter media from one of your established tanks, and chucking in maybe even a handful of gravel from an established tank to jump start your cycle. The bacteria you're looking for is in the filter media and gravel of your cycled tanks. Don't waste your money!!! Save it for fish!!!