I'm looking for some advice. About five years ago I had porcelain paving tiles laid on my patio and the installer used white porcelain grout. It is now starting to show gaps and I'm looking for some advice on the best rated white easy grout for exterior porcelain tiles to refurbish or should I completely renew the old grout? I like the striking lines of the white grout and would prefer to refurb or replace with the same appearance.