Would water volume itself be an issue here? If the device is built in-place so that just a cylinder edge and the bottom is mined out, the rock can be used immed

Would water volume itself be an issue here? If the device is built in-place so that just a cylinder edge and the bottom is mined out, the rock can be used immediately without having to mine it out or replace its' volume with millions (?) of gallons of water. Also it should be able to lift higher than water without a tank to hold it.