@GoGrabTheNet I've been looking forward to the next update too! ;-)
I hope everyone's having a good weekend. A quick update with some photos from yesterday. On Saturday, I threw 4 or 5 Tri-chlor pucks into the deep-end and let them sit there for a little while moving them around occasionally. At the same time, I jumped into the pool and spent an hour or so grinding another tri-chlor puck against the pebble on top of the stain. I'm going to declare a moderate victory. There's still a difference between this stained area and the surrounding walls, but I'm thinking that it's because I've probably been scrubbing this area pretty vigorously with the wire brush. Remember most of the pool has a coating of calcium on it that looks like a fine dusting of snow on the pebble. The good news though is that the stain is now no longer the yellow/brown color it was. The bad news is that it does seem slightly darker than the rest of the wall.
We let the kids in the pool on Sunday for the first time this year and had a blast, so things are looking up ;-)
Most recent set of test results:
FC: 4.8 (20 hours ago)
CC: 0.0 (20 hours ago)
pH: 7.6 (20 hours ago)
TA: 190 (2 days ago)
CH: 180 (6 days ago)
CYA: 30 (6 days ago) Need to re-test with the tri-chlor pucks. I figure about 1 whole puck ended up getting dissolved in total).
Early on in this journey,
@JoyfulNoise mentioned doing a no-drain acid-wash (Zero-Alkalinity Treatment) to dissolve the calcium scale. Any thoughts on if that's the next step at this point? I would imagine, this would drop the TA (which needs to be done), and increase the CH (which also needs to be done).