I've received a lot of hoyas with hard water spots. New growth comes out shiney and beautiful. My tap water doesnt leave too much of that build up.

I assume you don't have access to rainwater. If it bothers you that much, maybe try a light solution of vinegar or citric acid. I would only do one leaf first to see if it causes any damage.

Thank you Jake, we don’t get a lot of rain here, I have tried the vinegar and that did not work, thank you again for the suggestion.

Hey Dee, google "Brand X Foliage Cleaner" (sorry I can't link it, I'm on a work computer). It's an amazing, non-toxic foliage cleaner that gets rid of most hard water spots, while also making the leaves "slippery" enough that mealy bugs and scale cannot adhere to the plant. I literally can't say enough good stuff about the product and use it on all my (non-fuzzy) plants.