How many bottles are recommended to be purchased? This video, https://www.youtube.com/watch?v=xdpbL1CdTpI&list=PLlm-zbUyZYErA2UriqmQimk-yEJS9tw9U&index=6, can also be seen at https://www.youtube.com/channel/UCuMET5d_G0IbZ7i-U0UWHUw. Top