Sand

[Parrothead]

I plan on having cichlids. I have a new 120 Gallon Tank that I just set up, it's been running for a week now. It stated out very clear then I added tetra bacteria and ph stabilizer, it cleared up in a matter of hours then the next day it was very cloudy. Today it's has gotten clear again but now the sand is turning black, what is going on with my tank? Please help, I'm afraid to go out and buy fish.

 

[SherLar]

I'm afraid that you may have an anaerobic bacteria buildup in your sand. This happens sometimes when the sand isn't fully aerated, which is difficult to do unless you have fish that keep it agitated, or manually agitate it your self.
My advice would be to agitate the sand vigorously, then do a pwc. Do this daily for a few days, and hopefully, your sand will clear up.
Also, even with chemical additives, it would still be best not to add fish until your tank has fully cycled, which will take several weeks.