28K inground gunite pool. Chlorine on high side for 5 days. Pool showed green tint 2 days ago, progressed 1 day ago, green this morning (can clearly see main drain). Vaccummed signficant brownish powder off entire pool surface this morning and brushed afterwords. Just tested with Taylor K-2005 showing the following results:
FC - 9
CC - 0.5
TC - N/A
pH - 7.4
cya - 90
Alkalinity - 180
Ca - 400
Super chlorinated 5 days ago, 3 days ago, and 1 day ago. Pool has been very difficult to keep balanced all season. SE Michigan.

Your comments/questions/suggestions are greatly appreciated!