I would have done the same exact thing with LR
.com rock and they have to ship it to me. Is there any way the rock could have been contaminated? Did you bring it home wet? What does Zach/Mike have to say about your experience? Is there anything else in your tank that could have died? That kind of die off from LR
.com rock is all but unheard of.
Don't put any straight RO
in there. That will cause more die off (of your beneficial bacteria) and you don't want that! Do an 80-90% water change with well mixed, aged SW
and see where you are on the charts after that.
I've been through some crazy off the charts ammo (spilled some food in my tank) and never lost a critter (no fish, inverts, etc). Changing the water a couple of times will bring your water in line. Then just wait for the cycle to settle out before adding anything else to the tank.
Good luck. Let us know if you find anything.