filter material

[D.Barta]

I have a 20 gallon soonn to be reef tank.My filter is a emp.400 just wanting suggestions on what to put inside filter

[barbra]

You can use it to run carbon if you like, but for a reef tank you will be better off with live rock instead of a filter like that one. They must be maintained carefully and consistently to avoid nitrate buildup.

[D.Barta]

I have live rock in tank should i fill emp. 400 more ruck rubble or some kind of media to filter water