How do you tell when live rock has fully matured?

[jassz]

I don't usually have those now (though occassionally there are trace amounts). I am, however, running a sump and a Fluval cannister filter, and I change water every week. It seems to me there are lots of factors that contribute to NH3 and NO2 levels.

So I guess my question is, will all rocks completely change? How heavy does the growth get?

[BlueAbyss]

Do you mean you started with dead, dry rock, rather than 'live rock'? If your tank is mature, you will know because there will never be ammonia, on a normal day... ammonia signals something is wrong.