rusty circles in sand?

[cinnamongirl]

I looked under my tank for the first time since adding live sand last night to see what my sandbed was doing and found that under my tufa base rock there appeared to be little circles of metal/rust. Could that possibly be? Here's a picture (http://reefcentral.com/gallery/showphoto.php?photo=78098) Could it be that something came out of that rock, fell into the sand, and is now rusting?!?!?! Or is it typical of a sand bed starting to mature? Ammonia and Nitrite are 0, Sal 1.025, temp 80, PH 8.2.

[Randy Holmes-Farley]

It is hard to tell, but it may be metallic particles that are rusting, or it may be algae, or it might even be metal sulfides precipitating.

Unless you seem them on the surface, I probably wouldn't do anything about it.

[cinnamongirl]

There's nothing that looks like that on the surface at all. Is there any test you suggest I run?

[Randy Holmes-Farley]

No. I'd just be careful to not stir up the sand down to the level and possibly get a burst of something undesirable into the water.