Depends if its cured rock or uncured. If its uncured the delicate organisms living on it may die and raise ammonia, nitrite, nitrates and phosphates. Then you will see an algal bloom.
If the rock is cured you may still see minor die off. I would mix your water and let it sit areated for about 24 hours. Make sure the SG level is 1.026 and then put the rock in. Monitor ammonia and make sure that you dont add any life untill the nitrogen cycle is completed.