Interesting that you used the normal pink antifreeze over Winter and normal city chlorinated water flush in Spring and you had the plastic cap go opaque white. Did you notice the color change shortly after doing the pink install last Fall?
I sent an inquiry to the maker of the Shurflo 255-313 water pump filter asking for feedback on why the plastic cap of their filter changes from clear to opaque white on RV's. I will share what they say....if I hear back.
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