You can try the XRotor ESC, but, i think you will still run into cogging issues. At bare minimum, with 8 motors, you need 300A to run them properly, and that is when the motors are running with a light load. Burst amperage could be as high as 550A on start-up. This is the ESC Blue Robotics...
Are you doing individual motor control, for submerging and moving around? Are the motors fixed for only up and down movement, or, are they also going to be directional? Do you already have the motors and ESC's?
That is way too light for the motors you are using, and, according to Blue Robotics, at 20V, each of those motors pulls 34A, so, if you are using 8 motors, and only 2 of those ESC's, you are way over drawing on the ESC. For the setup you have, you would need 8 of the 35A ESC's, one for each...