Looking to finally buy a good bait tank sometime this year. Creek Bank or similiar. Have a couple dumb questions. As these seem to be a recirculating type of tank, how do you fill them? Portable bilge over the side to fill? Do you fill with brown, muddy river water or fill at home with clean water and if so what about chemicals in a public water supply? How do you empty them without pulling a plug and having all the nasty water go into the bilge? Pump it out too? Thanks, have never even seen one in person.