The more I think about it the more I think this may be the perfect time to go to a cube tank. Nice thick acrylic/plexi,.. possibly a brick style (euro-style?).
2' x 2' x 2' ... With a proper T5 or LED setup, should look nice. Should be able to rig up a locking acrylic/plexi panel for the top; Four swinging arms, one on each corner, to hold the octopus in. I can have the whole setup made from extra thick panels. Match the top panels thickness to the rest of the tank; For uniformity and insulation.
I guess the biggest decision left at this point is:
Cold Water Octo with a sparse placing of safe corals & a robust cleaning crew able to withstand the octo's eating habits.
Cold Water Cuttlefish Tank,.. Unsure of the life expectancy of these cold water varieties.
Cold water Coral / Fish tank without an apex predator.
On a side note.. I've thought through using the freezer as a chiller for the tank & I think I've come up with a rather easy solution. Keep a large plastic container 60g+ within a large floor freezer. Within this container you will chill water for use in the tank.
My idea is to have a single line in & a single line out. In essence this system could be called a cold water closed loop container system. When the temperature within the tank needs to be brought into check, a temperature controlled valve will activate a powerhead which will transfer water from the tank into the chilled container of tank water located within the freezer. This will in turn cause already chilled water to be pushed from the outlet line located on the bottom of the water tank into the main tank/aquarium. This will ensure the coldest water will be returned to the tank & not the freshly pumped into water.
If the temperature of the home/room in question can be kept steady, then a system timed water transfer (pump activation) set at the proper intervals would keep the tank within it's temperature parameters with ease.. If I'm thinking the physics through properly.
A glaring problem that some may point out is the fact that the water within the container in the freezer will have a tendency to freeze solid. This can actually be kept under control quite easily. Set the thermostat on the freezer to 34 degrees Fahrenheit. Sea water will not freeze at this temperature due to its salinity; Keeping the water in motion helps to maintain this state. Place a small powerhead within the tank to keep a slow steady cyclonic motion to the water & you should be set.
I may mock up something this weekend to test the timed pump intervals vs the temperature controlled pump intervals. Both will work; Timed is just alot cheaper if memory serves. Keeping the inlet & outlet of the system running to the tank screened will be paramount to tank inhabitant safety. Be kinda funny seeing frozen fish/corals etc.. flowing into the tank from the chiller setup. Evil yet Hilarious thought... a brightly colored eel gets intot he chiller setup. I come home after work to find what looks like an Otter-Pop floating in the tank....
