IF your CYA level was high before you drained it is possbile that some had depostited in your plumbing and had redissolved after you refilled. However, I don't think you would have had enough in the plumbing to raise your CYA an additional 60 ppm or so! I would suspect that there is some initial cloudiness in your water that is skewing the CYA tests, perhaps from a nascent algae bloom or perhaps some calcium carbonate precipitating out from high TA nd CH. The latter is entirely possible given your TA of 170 ppm and pH of 7.8!