Epoxy putty help? Any suggestions?

[Aleforge]

I need to buy some epoxy putty to fix the crack in the bottom of my pool. I keep spamming the forums about my problems (sorry) but was looking through all the different types online and wanted to see if anyone has used any.

Obviously it needs to be used underwater, and as probably everyone knows by now my crack is fairly large so I need enough to fill it in the best I can.

I came across this: http://a.co/3u0kI50

It says it bonds underwater to fiberglass, but I was curious if anyone has worked with it? I am not sure how pliable it is, or how easy it is to mix.

Lastly, if you guys were applying this stuff over a crack would you rough up the area it's going to stick to? I wasn't sure if I should rub sandpaper on the area a bit first.

 

[pabeader]

I had a small hole on the edge of one of my steps. I used something called A+B epoxy. Seen here:

I did not prep other than to make sure it was 'clean'. Mixed as directed and squished it into the hole. Spread it around to taper the edges. It's white like my pool so you can't hardly see it.