Nitrite

[jam1e]

Hey guys, I have a 12 gallon tank. Only 2 weeks old, no cycle because of aged rock and live sand. I currently have a Paracheilinus mccoskeri (McCosker's Flasher Wrasse) in it. [Although I'm pretty sure he's a Flasher Mutt so maybe Paracheilinus flavianalis x Paracheilinus mccoskeri] {I digress} and an aqua-cultered Ocellaris clown.ParametersAmmonia: 0
Nitrate: 15ppm
Nitrite: .1ppm
Specific Gravity: 1.021
pH: 8.1
Alkalinity: ~2.2 Milli equaivalents per liter
Temperature: 79 Degrees F
So my question is whether a Nitrite reading of .1ppm is harmful to fish or for future inverts?
I performed a nitrite test on Saturday and it read .1. I changed the water on Sunday and performed another test today (Tuesday) and still .1.
My assumed possibilites:
Is my salt causing this? I use Oceanic.
..........
Maybe my blue sponge filter in the back canister? I cleaned it on Sunday when I did the water change so unlikely. I'm switching to floss soon enough anyway.
I'm also seeing some diatoms on the sand and I've heard oceanic salt can cause this so I'm considering switching to IO. I was just assuming that that is caused by the recent introduction of the clownfish; I added him yesterday (Monday), so maybe that is it.
Thoughts, questions, concerns, answers. Anything is appreciated, thanks guys.

 

[jam1e]

Well I just checked the water I've been using for water changes and it has .1 ppm Nitrite so I guess that solves the mystery, so question is, can I still use this water or is that level harmful to fish and inverts? and is this the cause of the diatoms or something else?