Live rock turned black

[durcfish]

Need a little help, when I setup tank some of my live rock got buried beneath the DSB, I didnt think anything of it, but as I have been moving rock around, i discovered the rock that had been buried has turned black, and smell terrible when I took it out of tank. What exactly happened and what should I do, I move all my rock to "holding" bins and moved my fish back into 10 gallon QT tank. It seems all the rock that was under sand is like this.

[lando]

Hi and welcome to the forum!! Sounds like the portion of rock that was under thr sand had some die off on it. Just check your levels and be prepared to do a water change. What size of tank? How many fish? How much LR? Good luck! Lando
PS--where are you at in MN? I live in Savage.

[durcfish]

Live near Forest Lake and have a 45 gallon tank with about 70+ lbs of LR in it. So is this normal? and can this cause a tank to crash?

[Atari]

One of the problems associated with pushing LR into the substrate.. or indeed with it sinking in by itself over time.

You will need to cure the rock again basically.. maintain normal conditions in the holding bins (temp, lots of flow etc) and keep doing water changes to preserve the life still in it. Once the levels are in line you can add it back, but you might consider placing a foundation of dry base rock underneath it this time.