The problem is research shows the existing voltage at the barrier - 1 volt per inch - is not strong enough to turn back all sizes of Asian carp. After last week's news that the monstrous jumping silver carp are likely within about seven miles of the fish-zapping contraption, the Army Corps said Tuesday that it is going to begin a new round of tests to determine whether it's safe to operate at double its current voltage. The Army Corps says new research indicates that 2 volts per inch is strong enough to repel all sizes of Asian carp; the barrier was designed to operate as high as 4 volts per inch.