I was finally able to get this project done last weekend.
I had previously bought 2 tubes of the Grey Sikaflex, 3 rolls of green concrete masking tape, and a large caulk gun at Home Depot.
On Saturday I started the taping of just one side of our pool, and once I started squirting the caulk in I quickly used one tube in about 25 ft. So I knew I would need more to finish my project. I decided to do one side only first to see how things went, and then go from there.
Once I had the first side all filled in I decided to start adding sand to the surface to make it look like grout. The sand I had on hand looked awful sprinkled on the surface. I was sprinkling it out of a plastic bag with a little hole, which made it impossible to get an even coating.
I resorted to going back to my original plan of concrete drilling a leftover blob of dark concrete I had saved just for this project. This made me a nice amount of dark grey magic dust. I then tried using the plastic bag method again, but it still was really hard to make it look even. I needed a shaker - so I grabbed an old jelly jar and drilled the top with a series of 1/16" holes to be my new concrete dust shaker. I found that the dust/sand would sink into the Sikaflex a bit, and get a little darker - so my method involved a light shake first, and then following up with a bit more dust one or two more times to get rid of the shiny surface and make it more uniform. I blew excess off at the end and touched up areas that looked light or needed more.
Below is a section of the finished product. I got pretty sore crawling around and slowly pouring out the caulk, and shaking on my magic concrete dust - however all in all it looks just like my coping grout. If it lasts a long time it will be worth it. One section I did in the heat of the day, and added a bit too much dust, so it cured a little less than perfectly flat in a few areas...
We are now officially done with the pool - we made our final payment to the pool company Wednesday after all the punch list items were complete!