The house I've just moved into is not old - built in 2016. My question concerns the shower in the main bathroom. It looks like the couple who lived in the house previously only used the ensuite, because the main shower looks pristine. One teeny concern though: on the floor there is a one centimetre hole where the grout wasn't pushed properly up to the wall tile. Now having seen what damage capillary action of water can do to old showers, I'm worried that this hole might be the start of problems in the future. Is there a tube of something I can buy from Bunnings - a grout filler - to bung up the hole? I don't want to buy a huge can of grout for such a tiny gap. And whilst talking about showers, is there a liquid I can apply to shower grout as a preventative measure against future hairline cracks in grout? I'm just trying to be proactive. Many thanks.