Every rare once-in-a-while, someone who knows something about swimming pools 'shows up' on the Forum to answer questions such as yours. I wish I knew someone who could help you more directly.
In any event, a gentleman named 'Hugh' a short while back recommended Hydrazzo. I don't know anything about it so I'll let you look into it. He left this link, Pool Spa, for a previous Poster. Maybe these folks can help you.
Also, I did a WEB search and found Pool Finishes. Companies that are mentioned regarding pebble finishes are: Transtec Inc. in Pass Christian, MS. ALso, there's CASTART by NatureScapes in Tucson, AZ. And about half-way down the page at Pool Renovations is info about Pebble Tec. There's also a finish called Pebble-Crete.
Maybe you need to get Pool and Spa News Magazine. (Check out the 'Articles Index' on the left of the page. You may fine more on what you're looking for.)
HOpefully, I've gotten for you what I call 'a good start'. My best to ya and hope this helps.