Cleaning limescale of bathroom floor

[Gravitygirl]

I think that our bathroom tiles are terracota and were the sink is there has been a leak and over time it has built up a layer of white around the bottom, which I presume is limescale.

Any ideas how I remove it, I was thinking ajax and scrubbing brush? will this be effective?

Any ideas for anything less chemically would be great.

Thanks

Neat lemon juice is usually good for limescale but I'm not sure if it would react in some other way to the tiles - terracotta is quite porous. Maybe test some lemon juice (or vinegar) in some out of the way spot first?