What is this??

zx636r

New Member
The tank has only been running for about 2 months. It finished its cycle and got balanced
out around 3 weeks ago. I've got about 15 pounds of live rock that came from a well established reef tank, and about 15 pounds of rock that was live a while back but had since dried out. The "dried out" rock is the one I have a question about. The rock was really white for a while (as you can see), so I started using purple up every now and again (not as much as they say to on the bottle, just every couple days a SMALL amount) hoping that I could get some good color on it. Well the rock has started to turn a strange rust looking color. Some of the color is on my sand also. I don't know what is is, but it doesn't come off the rock if you just touch it or scrape at it. So I thought it might be coraline but I'm a noob and have no idea. :thinking: lol Thanks for your time.
Forgot to add. I don't know that it matters but I put new lights on the tank about 2 weeks ago. Its got 130 watts of PC and the tank is about 18" deep. Thanks again
 
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