My preferred anode is some 1" heavy gauge expanded metal. There is lots of surface area, allows water to move through readily, and is lightweight and easy to lift out, give a flop against the ground, and all the rust falls out. Granted, my main tank I also have a 14 gauge bottom that is wired up to my negative cable so I don't have to wire or link multiple parts together, just make sure that the are sitting somewhere on the bottom of the tank.
My preferred electrolyte is sodium hydroxide.
