Electric charge on pool?

We have an electric charge on the pool like Lonewolf asked about 4 years ago. 2 pool guys, 2 electricians, and an engineer, none could solve it. It's fiberglass. When all power is off to the house, there is still a charge. Not while in pool, but if you are touching the concrete and touch the pool you will get buzzzed, petty good if you touch the metal rail at the same time too. Much less if you touch wood at the same time. Not at all if you are on the plastic liner edge only when you touch the water. Seems to be increase when running the vacuum thingy and filter. Seems to dissipate when those aren't run but have to run them some or the pool turns green. Help!