I am looking after a pool for the first time this winter and I am going to be absent (abroad) most of the winter so would like to winterize it. However the pool has gone green and I have half drained it so it is half full, and put lots of chlorine in it. I have left it now with the filters off (as the water is below filter level anyway). I am worried that the algae will stain the grout between the tiles of the pool, does anyone know if this will happen if I just leave it green? Also is it ok to leave it half full and is there any way in which I can get it clear again within 4 days as this is the max time I will be available to try and cure the algae before being away working again!