I always was concerned about putting my Octo into the sump, as I had a hang off the back overflow on me. Emptied about a third of the tank. Don't want that to happen in my sump. I spilled a cup of the filth into my tank once and instantly killed three fish, and forget how many coral. Where can you drain a skimmer to when the tank is in the basement, and be able to contain about 5 gallons of water?How do you mean? My 150-SSS and 250-SSS both had a plug that I could drain off into a container.
I just found it not necessary.
I skim pretty dry though.