If the water is shut off during the filling of the pool after new pool finish application it is highly likely that there will be a visible difference in the finish at the point where the water stopped filling. This is commonly referred to as “ring around the bowl” and is caused by the fact that the dry pool finish material will hydrate at a different rate then the submerged finish. Simply put the section of the pool that stayed submerged will look darker than the section that was allowed to dry out. It may take over one year for the finish appearance to even out if this situation arises, and may require remedial action to rectify.
“Based on temperature and type of finish, fill the pool to the middle of the skimmer or specified water level without interruption as rapidly as possible with clean potable water to help prevent a bowl ring.” National Plasterers Council, NPC Start Up Card, September 2012 edition