Here's what I used:
Epoxy Grout Parts A&B https://amzn.to/2OEpvae
Epoxy Grout Part C https://amzn.to/31FUHet
Epoxy Grout Trowel https://amzn.to/38fkFIe
3M Painter's Tape https://amzn.to/2tJpwCF

My shower was leaking and it was essentially brand new. Only 3 years old and we spent a lot of money on it so I was hugely aggravated. Another Youtuber, starrtile, suggested I try epoxy grout so I did. I will show you the step by step process, some tips, tools, and the results. I am now a fan of epoxy grout and will definitely require it in my next tiling project where damaging leaks could be a concern.