I found some interest here in 2015 in biorock accretion. I am about to start a series of tests I hope will allow the formation of island size structures. From my reasearch so far bio rock is stronger than concrete and was origionally developed for industrial use. It appears that the inventors have used it to create breakwalls and restore beach.
Several techniques i am theorizing will increase strength and accretion rates.
Layering the electrode. I plan on adding layers of electrode as the process continues so that conductive material is always exposed during the growth phase.
Increasing growth rates via increased surface area. More surface area means the holes close faster. I plan to test steel wool, hydrocarbonated biomass, 1 inch carbon fiber chop expanded steel, wire meshes, bug screen. another byproduct of using a fiber is that you are essentially creating a carbon fiber reinforced bio concrete.
Materials I plan to test spray on carbon electroplate conductive base paint on various non conductive materials such as foam and plastics. I plan to use charred wood for electrodes as it is conductive. I have a hunch it will form within the wood fibers creating a synthetic petrified wood.
Synergy. Im hoping that by doing all these things together it becomes feasable to acrete large strong hulls.