That was the biggest expense in this setup, the chiller keeps the water at 56F for the creatures. The Tidepool sculpins are pretty small, and I think the largest one I have seen at the Seattle Aquarium was about 3"
I have been suggested the Catalina goby, but since I have a biotope I do not want to introduce anything that is not part of it. They are adorable, though!
All the marine life in that tank has been gathered near my house. The sand substrate is Quikrete Play Sand.