Just doing an update. I spiked the water with a very small amount of Ammonia yesterday, but curiously enough the water tests both later in the day and this morning showed hardly a blip. Ammonia is still at 0.25, perhaps a bit lower, and both Nitrites and Nitrates are showing at 0. The pH is a little low at 8.0.
However, something is indeed going on in the tank. There's a brownish algae which I presume is the early tank Diatom bloom. It's growing fairly rapidly, here's a picture of it this morning:
And then early this afternoon:
I understand that the diatoms are simply a natural development and they'll eventually go away... especially after the clean-up crew is added. However, I am not entirely sure the tank has had its initial ammonia cycle yet despite me spiking the tank yesterday. I've seeded the tank with Beneficial Bacteria, but I'm still waiting for the spike in both ammonia an nitrites before thinking of adding in the clean-up crew.