Your tank will cycle without NOPOX. I'd say save the NOPOX (and the hard earned money you spent on it) for after you're tank is cycled and you've added a fish and a few hardy coral... You will get diatoms (that yucky stuff on your rock and sand) as a NORMAL part of this process.
Here's a brief synopsis of the nitrification cycle: Ammonia gets processed into nitrites and then finally into nitrates by the benificial bacteria you introduced by adding a piece of shrimp or any of the off the shelf products. Nitrates are the last step in the cycle process.
So, just let the tank cycle. Test every couple of days and chart it if you'd like to monitor the cycle process. You should see the ammonia spike first and then gradually decrease, followed by a rise in nitrites and then it too will decrease as the population that processes nitrites increases. Finally you should start reading some nitrates - cycle complete. So, when you get done do a water change and start adding a few hardy coral and a fish (go slow).
Now you have to figure out how to manage the nitrates and phosphates. Cue the NOPOX. Hope this helps.