At the moment I am waiting. The sump is a standard 55 gallon. I plan on part of the sump being a frag tank. RLSS has rubbed me the wrong way, so I decided to go with a Super Reef Octo for now. Probably the SRO3000 internal. After realizing the size of this skimmer, I am worried that there wont be much room for a frag section in the sump. Now I am thinking of the external SRO3000. There is room for the external, but I dont know if I can place an external at the same height as the sump. Im not sure if the external skimmers have to be above the sump to avoid overflow issues. Depending on the answers will depend on the skimmer. Monday I make phone calls. For now, I wait.