I have a small bathroom with the old style, aqua-bluish tub/toilet and sink. What color paint should be used to calm those down? The floor has a very light shade of blue tile and the counter top is white with blue swirls and stained woodwork.
When you have a color you want to downplay, the first rule is "don't fight it". Find a soft neutral that will subdue the tone, and then bring in accents with colors to distract the eye. In your case, with aqua, I would go with a neutral that has a touch of green/gray to harmonize with the green of the dominant color. Take a look at Cliveden Mist or White Scallion. Then bring in colors you do want to emphasize through your shower curtain, towels and bath mat/rug. Try bringing in rusts or deep coral/roses in small doses. You could also try bringing in navy which can look very crisp and modern against aqua. Let us know how it goes!