Rocks for Cycled Tank

[salty27]

I have a 50 gallon, Fish Only, cycled tank (established for over 2 years now), with dead/frozen coral and a few pieces of solid rock. I run a cannister filter and protein skimmer, and use crushed coral as my base. I have been toying with the idea of changing the scenery up a bit for my fish by adding different pieces of rock for stacking and creating more caves and hiding places.
However, many years ago I once introduced rocks (not sure what type, but they were very porous) to an already cycled system that completely threw my water out of cycle and killed all the fish in my tank in a matter of days. To avoid this mistake once again, what kind/type of rock should I be looking for? Are there any risks that introducing any rock could once again throw the water balances out of whack? I was thinking of buying some chunks of dry stone(?) I saw at my LFS, which looked ideal for the new scenery I envisioned.

[roka64]

I buy mine already cured, from the LFS. More than likely the rock you introduced caused a huge ammonia spike, due to the die off from the rock.

[melosu58]

Originally Posted by roka64

More than likely the rock you introduced caused a huge ammonia spike, due to the die off from the rock.

This is exactly what happened. You have to buy already cured LR or you have to cure it yourself in a rubbermaid tote. If you need directions on how let me know

[salty27]

Thanks melosu. Though I'll probably buy the rock already cured, your do-it-yourself directions could be helpful for future reference. I appreciate it!

The one weird thing from my last experience though, is that the rock I introduced (which killed off my tank) was bought dry. I never thought there would be die off from dry rock.

[roka64]

It could have been anything from copper to pesticides or something that leached into the rock, bleach or anything. It is hard to tell. Plus the die off was alreay on the rock and the SW caused, possibly, an ammonia spike...

[Ziggy953]

I agree with the fully cured live rock. When I set up my reef tank I used cured LR and LS to start it up. A bit more expensive then other routes but better I think!