Well hi there. letting you know that this coming year is going to be cool. Starting with keeping all of your stone and tile clean and sealed repaired and just plain ready for anything that hurts it. We are starting this today with calcium removal from areas in your pool and coping and Pool decking. the big white line around the inside of your pool is usually calcium and or hard water deposits that stick to a finished that hasn't been sealed properly or with a weak sealer. To seal it right will make water and deposits slide off and not stick to the walls or tiles .