Grout or silicone in leaky marble-tiled shower?

[potato80]

Hi all

My old marble-tiled shower (pictured) is leaking from the gaps between the tiles.

I think it's mainly coming from the hairline gap that runs along the bottom edge of the tiles, where they meet the shower tray, but I'm gonna re-do the whole lot anyway.

My plan is to use an oscillating tool and diamond-tipped blade to carefully remove the old grout.

Should I then use grout or silicone (or grout then silicone, perhaps at the bottom edge) to repair?

Thanks in advance

 

[sircerebus666]

Remove the old silicone , grout , then on top of that do a silicone bead all-around the edge of the tray and tiles to the side of the tray

Dow Corning silicone is very good

 

[potato80]

Many thanks ✌