sand issues HELP

[trd47]

here's the deal my tank has been up since august 30 my rocks has been cured for over a year. my sand is real fine and white. lately I've been seeing my sand go from white to brown, I usually try not to stir it up but lately its been bothering me. yesterday I stirred my sand up and returned to its white color. today when I go and check it its brown with some white patches (areas which are unaffected). I also notice some brown caramel speckles on my tank on the glass which I scraped off.

then I decided again to go stir it up and notice there are some sand which are like black, greyish in color. this sand is found under my live rocks, what gives? although the live rocks that are not burried deeply have perfectly white sand under them.

can any offer some insight to this?
browning of sand and some black sand under live rocks which are burried under the sand.

nitrites-0
nitrates-0
phosphates-0
ammonia-0

btw im using my wavy sea which is connected to my mag7 and water has to travel about 4feet as my return and powerhead. its doing fine because the wavy sea is able to disturb the bottom of the sand. I haven't been feeding much lately to try and resolve this problem but nothing!

please help!

[pikachusalad]

The brown stuff sounds like diatoms - normal for a tank that age - pretty much nothing you could have done to avoid it in a new tank - there are a number of threads with advice - water changes, increase flow, get some cerith and nassarius snails and maybe a fighting conch, reduce your lighting period, etc. Long as your tank has good flow and water quality, it will go away eventually.

The black sand...I'm not sure...but it could be something not so good... I'm gonna let someone with more experience answer that.

[bertoni]

The black sand might be caused by cyanobacteria or perhaps by anaerobic microbes.

What kind of cleanup crew is in the tank? What is the setup like?

[demonsp]

How deep is this SB and what is the cleanup crew?

[Percula9]

Just as long there is no rotten egg smell coming from the dark areas. If there was that means hydrogen sulfide would be present. Not a good thing. Get a sand goby to mix the sand up and reduce the brown diatoms.