Dear Rabbi Kornfeld,
I am referring to the last portion of your requote starting with Chachamim. How is this the view of the chachamim when Rashi points out that the Rabonim require both shiur and chazut of mayim sheuvim in order to posul the mikveh, while we see at this juncture that the Tana Kama disregards the color of the mixture, that is he posuls the mikveh even though its not the color of water.
The Gemara first brings the Mishnah with the text 'Chaser Kortav' in both clauses. According to this, Chachamim require only a shiur of Mayim She'uvim in order to Posel (the first Rashi DH Lo), so R. Chiya is like Chachamim. Later the Gemara says that if the text in the Reisha does not say 'Chaser', Chachamim require also the appearance of Mayim to Posel (Rashi DH d'Bo'i). Indeed, if so R. Chiya is unlike Chachamim.