Abstract: A method and apparatus for installing a mounting support for upright supporting posts in pools, particularly of the type having a vinyl liner. A hollow tube having a closed lower end and a coupler collar at the upper end is embedded in the ground defining the bottom of the pool. A top plate and gasket are secured to the coupler collar with the vinyl liner positioned therebetween. An upright post for a swimming pool accessory may then be easily engaged in or disengaged from the mounting support. A pop-on cap may be fitted to the opening of the mounting support when the mounting support is not in use.