Thanks everyone for all the help so far. But I have two more questions. About ten days ago, I started cycling an Oceanic 29 gallon bio cube. It has 1 1/2 inches of live sand, about 30 pounds of live rock in the tank, and I replaced the bioballs in the filter with about another 8 pounds of live rock rubble. You guys told me about a nano skimmer (it's made by Tunze) that can fit in the filter of the bio cube -- but if I get it I will have to remove all or most of the live rock rubble to make room for it. Which is better -- the extra live rock or the skimmer? Also, should I use the skimmer while the tank is cycling, or wait until the tank is ready for an octopus to turn on a skimmer? Thanks again.