Hello all, I am in the process of converting my 60 gallon freshwater tank to a salt water tank. I had 2 Red Ear Slider turtles and now they are now currently enjoying a new pond in a buddies back yard(I felt they were getting to big for the tank). I would like to convert my tank and possibly take on the responsibility of a Octopus. Right now the substrate in the tank is sand. Should I replace all sand or is it ok? I have 2 canister filters Cascade 700 and a Cascade 1000 basically enough filteration for 160 gallons. I understand that there is a time frame in order to prepare the tank for the Octopus. So I figure the earlier I start the earlier we can get the octopus. Any thing you guys can fill me in on would be great.