Diatoms/algae?

[Sonatine]

My tank's been up for just shy of two weeks (cycled with bio spira plus a small amount of live rock from LFS).

One of my rocks (the live one I bought) has developed a brownish rust colored coating. Is this the start of diatoms? Pics:

This pic makes it look much more green than it appears to my eyes (I see mostly brown with a few hints of red, no green at all) looking at the tank. There's also a few little filaments developing:

So far, only the single live rock is affected (though it looked almost like my dry rock when I got it), no signs of growth in the substrate or on the other rocks. There's a few deeper red patches that almost look like they might be coralline algae but it's hard to tell for sure.

My main question here is whether it's time to start adding a CUC (currently I don't have any inverts at all). I don't want to push the tank too much since I just added my second clownfish on Saturday, but I was thinking about maybe getting some snails this week and just riding out the ugly phase if that's what this is.

Ammonia and nitrites have been zero, nitrates have also been reading zero but I'm not sure I trust that since I was using API. I don't yet have tests for phos, etc but will be getting them in the near future.

 

[Mr. Mojo Rising]

sounds like it is time to get some snails, and proper test kits. You cant really just "ride out" the ugly phase, or the ugly phase will soon completely take over your tank. You need to actively fight and control it all the time, for as long as you have the tank.

 

[Sonatine]

sounds like it is time to get some snails, and proper test kits. You cant really just "ride out" the ugly phase, or the ugly phase will soon completely take over your tank. You need to actively fight and control it all the time, for as long as you have the tank.

Snails it is. I have the seachem ammonia alert at least, but I'll look into some non-API tests to grab, and go from there. By "ride it out", I meant more "start managing it without being overly stressed", rather than "do nothing and see what happens". It's cool to see the tank changing a little bit every day, even if maybe that change isn't super pretty yet.