Perfectly normal result, when you have very high chlorine levels. High levels of chlorine convert "phenol red" to "chlorophenol red", which is a different indicator. Don't worry about it! If you are using nothing but bleach, your pH won't change too much.

What's the texture of the ring in the skimmer? (It could be organic debris, from all the algae & slime . . . including white mold.)