White film around tub

[riddler]

My mother has a tub , but no computer. Go figure. The problem is she has a white sort of chalky film on the upper edge where the water line is. you can scrub all day , but it seems you cant get rid of it. Any solutions how to get rid of it , and what is causing it. Thanks for any input.

[Chas]

Tell her to try lowering the ph and total alkalinity. She does that by adding "spa down" or "pH minus" or something like that. She'll have to work for a day or two to keep it down. After several days, the white stuff should be gone. After that, change the water.

[rocket]

I've seen this in my area.  Think that its calcium deposits.
Try a soft sponge and baking soda.  May help.