I don't have any comments on how to solve your problem but am curious where your house and pool are located in relation to other houses. When I lived in New Jersey in a housing development you could stick a couple rods in the ground and get a voltage reading. Here in the country I get nothing. Ben touched on it when he was talking about power companies using the earth as a conductor. They don't do it intentionally but it is a fact of Ohms Law. Residential power is supplied by the live high voltage line and a neutral, or return, strung on the poles or underground. A transformer drops it to the 120/240 single phase for the house or houses. Because houses have these 'neutrals' connected to water pipes etc, part of the power distribution systems return current will flow through the earth thus creating a potential difference between your house and a neighbors. If neighbors are close this voltage gradient in the earth can be high. In the country with houses far apart it is a lot lower. Theoretically if all your pool equipment, rails, etc were connected to your service entrance neutral with a good heavy, low resistance wire, you shouldn't see this gradient.
I'be babbled enough.
Al