Thanks for that link! I'll explore it after writing this.
The main reasons I visit Clark's are that they're close to Downtown and they do have knowledgeable people. I learned Saturday that they'll take my extra water sprite, too
I think I've seen Rocky Mountain Stone while out with car-driving friends as we zip by on I-25. If I had a yard, I bet that would be the place to visit if I were to make a pond. Maybe if my boss decides to spruce up our pond at work I can suggest looking there. As for smaller rocks, I use pretty much exclusively jasper, quartz, and petrified wood, plus common aquarium gravel.