I'm posting this here since this is the area for pipes. I want to keep my pool open this winter but would like to not have to run the slide to keep it from freezing. There is a black plug below the on off valve for the slide and for the other pressure side return jets. It looks like it can be unscrewed but I'm not sure. Since the equipment pad is below the pool I'm thinking that if I unscrew it and the valve is turned off, the water will drain out of the pipe and then all I have to do is keep that valve closed during the winter. Does it unscrew? Thanks!