Adding dead rock

[asylumdown]

It really depends on how much rubble we're talking about vs how much matured live rock you've already got. It's been my experience that a mature system with enough rock for it's volume and occupants is pretty resilient, as it's got a whole battery of processes in place to deal with waste above and beyond the nitrogen cycle. You've also got thousands and thousands of teeny little critters that will go to work eating anything organic before it breaks down in to ammonia. If you're talking a relatively small amount of rubble compared to what's already in there, you're likely not going to notice a thing except for the gradual colonization of life back on to the rubble.

If you're really worried test for ammonia a couple of times over the next couple of days. If you see any sort of colour change, do a water change and add some prime, but I bet you'll be fine.