Well ok, lol. I did a bit of stuff with Fritzyme 9 and it appeared to be full of heterotrophs, not true nitrifyers. I concluded that by the time it got to the UK it was pretty useless, link attached;It doesn’t and your right.
If it gives the reefer “piece of mind” then by all means.
We just don’t do it in our set up’s any longer.
https://www.reef2reef.com/threads/fritzyme-9-modified-cycle.999904/post-11641849
