How to clean white surface on newly layed colored grout

I have recently regrouted tiled balcony in my home. Now it is about one week after the completion of the regrout. I found the grout surface becomes white. If I put some water onto the grout, the white surface disappear but then reappear after the grout dries. This possibly suggests that the white color stays on the surface only.

I thought the white surface is because of some white powder and tried to clean them using mop. Not effective.

Any suggestion on how to remove the white surface? My grout color is Cappuccino. As I planned to seal my grout soon, should I clean the white surface before proceed?

Thanks


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