Grout Haze Question

 

I am redoing a bathroom using porcelain tile (Meridiana tile) with a border accent of tumbled Marble (http://www.lightemprador.com) .  The installer is grouting today with unsand (http://maplered.com) ed grout and (http://maplered.com)  Super-Tek acrylic grout additive.  He told me to use a 50/50 solution of water and (http://maplered.com) vinegar tomorrow to remove the grout haze.  I am afraid to use the vinegar solution because of the tumbled Marble (http://www.lightemprador.com) .  I am afraid of etching.

 

Could you please advise me what I should do tomorrow to remove the grout haze.

 

Thanks,

Rosanna.