Bio-spira will give you good readings in a very short period of time. However, I question it's longevity. The main prolblem with this type of product is that it really gives you a false sense that you are ready to add fish. People us this, add fish (most of the time too many too fast) and then wonder why their water parameters are all messed up and fish are dying of ammonia posioning. From here on out it is a constant struggle to keep paramters at acceptable levels. It just does not prepare the tank to support fish long-term. If you are an impatient hobbiest (it is hard looking at an empty tank) youcan use this product to jump-start the cycle and maybe add a fish to finish things up. Bottom line...there is no substitution for cycling the slow and natural way.
Some people are like slinkies...they serve no real purpose yet can still bring a smile to your face when you push them down the stairs!:p
Have a great day! Brian