Here are a couple pictures of the staining. I will try the baking soda test this weekend and get water tested too. Wondering your thoughts on the appearance of this stain. Water is shocked and pool completely vacuumed.
https://mygoodoldhouse.files.wordpre...08/photo-1.jpg
https://mygoodoldhouse.files.wordpre...08/photo-2.jpg
https://mygoodoldhouse.files.wordpre...08/photo-3.jpg

http://mygoodoldhouse.wordpress.com/2014/08/08/pool/