rock curing

[fiorano]

i know that this is a question asked all over the place ... but anyway i bought new rock and someone told me that its actually better to let the rock take care of itself and eventually all the nitrates will get taken care of by bacteria and such. but i bought this rock like 2 months ago and the ammonia- nitrites all went by fine ... but now the rock is hung up on nitrates. so should i just do water changes till the nitrates are gone or if i actually wait long enough will the nitrates start declining. they have been pretty much the same for around 1.5 weeks or so. thank you for the help... sorry for the stupid question haha i should know this by now