It was black and after some brushing turned light brown. Its in my deep end and water is 63 degrees so getting in and scraping is a bit problematic.
Here are some hot off the press numbers. My CYA jumped on me, guess those trichlor pucks do work but they sneak-up on you. I tested three times to make sure. Standing in sun with back facing sun and test belt high in shade from my body. Makes sense though as it's been quite warm here the past week, mid -to high 80's, my pool is in full sun and I've been maintaining 6 to 6.5 FC with three small pieces of puck in the floater left. Until today SWG hasn't been on and right now it's only at 10% having run a total of 4 hours today.
FC - 6.5
CC -0
pH - 7.6
TA - 80
CH - 1050
CYA - 70
Salt - 3,500
CSI - .08
In terms of seeing a reason to slam the only reason is that's what my plaster guy told me to do to get rid of the "organic" material (this is what he called it) at the bottom of my pool. Tried nylon and steel brush and hasn't been working. Went and picked-up bleach and I'm ready to roll if people thing shocking is still a good idea.