Nutrafin Cycle Effect on Actual Cycle?

Nope. Cycle is generally considered little more than snake oil. Bacteria must eat, and in a bottle formula, this means they have a limited shelf life. This particular product has never been proven to impact the development of bacteria.

Bio-Spira, a relative new comer to the market, has in fact shown to provide the tank with an effective innoculation of bacteria. It must be refridgerated. More stores are beginning to carry it, but it can be difficult to find.

What it really come down to, though, for all products and cycling methods, is the test results. Ammonia and nitrites must first show up, then test 0. With products like Bio-Spira, there should be only low levels of ammonia, if any. If the fish are in the tank for more than a week (assuming an appropriate stocking level for the tank size), and there are not detectable ammonia levels, then it's safe to assume that the bacteria bed is present.
 
I have used bio spira with great results on a 100 gal. tank. Many are skeptical because of so many products claiming the same thing in the past, but you actually add your full load of fish immediately after adding the proper dosage of bio spira. It worked for me with no stress on the fish.
 
One thing about "Cycle:" anything that will break down in the aquarium will release some ammonia in the process. There is always a small "founder population" of nitrifying bacteria.

So anything that is biodegradeable will work to start the cycle. Even an oatmeal cookie.

The success of Bio-Spira is emphasized by the crop of imitations and "new improved" versions of old products.
 
AquariaCentral.com