Rock that is purchased dry can still contain dead or decaying organic matter, even if it is pressure washed and cleaned thoroughly before putting it into your aquarium. The introduction of this new rock can cause spikes in both ammonia and nitrite, which could lead to livestock stress or even death. To prevent or minimize any cycle that may occur, treat the dried rock as if it were like regular live rock. Pre-cycle the rock in a tub of saltwater and plenty of water circulation. Perform complete water changes on the tub of rock to accelerate the cycle, and keep bugs, leaves, any other organic material from getting into the tub and decaying, as it would prolong the cycle time of the rock.