Tile terrace sealant
 

I'm not quite sure what I'm asking here, but basically I want to try and stop any growth on the tiled terrace we have, especially on the grouting between tiles.
On the flat edges of the terrace, it causes green streaks down the house when it rains, not good!

Has anyone used anything they can recommend? I had a brief look but there were various products, some VERY expensive and I'd rather go on a recommendation!
Also, most seem to be coloured, am I daft to want transparent sealant!?

Thanks ;)

Re: Tile terrace sealant
 

Sealant I would not use as it may well be very slippery when wet.
Bleach mix should remove the mould, or Jeyes fluid will ! (sold in Iceland)