While I personally agree with not vacuuming the substrate the amount and frequency of the water changes is directy related to need. In your case you need
to do them more often and weekly. The tank is quite young still and although it can cope with NH3
, the anaerobic/anoxic bacteria that convert nitrate so it can safely leave the system most likely are in their infancy (mass wise) of haven't even formed yet. It can take quite a few months before NNR
will occur. Just keep up with the weekly water changes and only feed every second day. Just be sure there is always some type of Nori or other grazing food for the tang. It will start coming down, you just need to be patient a few more months. For your current bioload the amount of rock you have is fine but if you decide on addition stock (waste producing) I would suggest another 50-80 lbs.
, I would seriously suggest returning the anemones. A 2 month old tank is far too young for such a delicate invertebrate and should only be housed in a well established tank (1+year)