White Stain Removal

[Chiefblue]

Does anyone know the best way to remove these white stains? There is some be the control panel and in the drink holders. It seems like it’s leftover after the water has evaporated. Thanks in advance.

 

[RDspaguy]

What is the shell material? What brand? What color?
For acrylic, a 50/50 mix of muriatic acid added to water. And, of course, time and elbow grease. The more time the less elbow grease.
DO NOT USE A SQUIRT BOTTLE. Acid mist is BAD. You can soak a WHITE rag and let it sit for little while on the tough spots.
On a plastic shell I would make it a 25% acid mix and use more elbow grease than time.

 

[Chiefblue]

I believe the spa shell is made of H.D.P.E

 

[RDspaguy]

So... plastic...
I have no personal experience with it but I have heard that acid can discolor plastic shells. So a weaker mix and less exposure time (so more scrubbing) is the way to go. Use a plastic bristle brush not a kitchen scrubbie.