White film in bottles

I bottle my beer.

I rinse out bottles immediately after drinking, then let dry.

I sanitize with starsan just before bottling.

I am starting to get a white residue on some bottles. The residue is on the glass and goes from the bottom to the neck (point where the top of the beer line was). It appears to be a soapy residue. Hot water does not remove. Bottle brush scratches through it, but still leaves some, mainly near the bottom corner of the bottle where the brush has a hard time getting to it.

What is causing this......and how do I remove??

Thanks to all,

John

Sounds like ut could be beer stone. You really need to clean with something like a pbw and scrub, then wash with starsan and then scrub, make sure it is clean and then give it a rinse with starsan.