Put it in a media bag and you can run it in a HOB
filter, like your Emperor, or place it in a high flow area of the sump if you have one. Be sure to change it frequently, ie. about every 7-10 days. After that it's useless and it can cause problems like raising nitrate levels. Along w/ keeping water clarity high and allowing better light penetration, GAC
is useful in reefs b/c it may remove some of the toxins corals release when competing for space. These toxins, called allelopathic toxins, are found in much higher concentrations in aquariums than around natural reefs and they can inhibit growth and overall health of the corals.