nitrate ?

[steve_karen]

Is it absolutely necessary to have a refugium to have low to 0 nitrates?
Would a good skimmer, live rock and a deep sand bed prevent a nitrate problem?

[Dholmblad]

It is not, but any added ammount of water to a reef can help alot.

[GoTakuF1]

The best way to prevent a nitrate problem is not to overstock your tank and keep up with maintenance. Good luck!