Sand discoloration

[Steve Maxwell]

My tank is almost a year old and within the last couple weeks I've had some sand discoloration. It is Carib Sea Ocean Direct Caribbean Live Sand (which I hate btw). I've tried vacuuming it up, but it just comes right back. Any ideas what this could be?

 

[twilliard]

Excess nutrients in the water

 

[Steve Maxwell]

Hmmm...I just had a thought. I have been replacing some of the sand that gets sucked up in my vacuuming with the "live" sand that I bought a year ago that is still in the bag. I've been putting in a few handfuls at a time, but have just realized that I haven't been rinsing the sand. The sand in the bag doesn't stink, but I highly doubt there is anything "live" in that sand. Could that be contributing to the excess nutrients? The only change I've made in quite a long time to the tank has been adding a tuxedo urchin.