Time for an update and a couple of questions to check in on what I am seeing.
Shocking is continuing, and the FC levels are holding moderately (losing 1-2ppm overnight without filtration, 3ppm in 4-6 hours during the day with filtration and low cya). Monday, I noticed a few issues with the filter grids, so I bit the bullet and replaced the entire set yesterday. The filter is still reaching the 10psi increase in 60-90 minutes (requiring a backwash), but the initial flow through the returns is noticeably better. So now, with new grids and the FC holding, there are two things I am seeing that I hope you'll chime in on.
1) Color! The color is changing, but not to the milky-white that the pool school articles suggest. The color is slowly changing to more of a yellowish-brown. Also, the color change is more apparent in the shallow end and less in the deep end. Does this make sense?
2) Each time I finish the backwash/rinse cycle and switch back to the filter cycle, when the flow first passes through the returns (before I even have a chance to add DE) I see an initial plume that looks like a white cloud passing into the water. It only lasts a few seconds, but it is noticeable in each of the 4 returns. Any ideas on this?
Thanks, again, for all of your input!