I apologize for my mistaken wording but I meant to say that, "the former "aa" is the sharp and jagged"
I have some of it in my quarantine tank. I took it out of my community tank because I did not want the Corydoras paleatus to damage their barbells on it. They are also bottom feeders that enjoy clinging and hovering closely on hardscape.
As for the sand, P. kuhli swimming up and down the walls of the tank is nothing to be worried about. This behavior is one of the reasons I enjoy keeping them. The fact that they want to be seen means they are feeling comfortable. I do not think that collecting sand from your back yard is the best practice, but I use home made soil for substrate so I guess as long as you trust the source you are fine. If anything bad happens to those guys you have another variable to account for when trying to diagnose the problem. There is more gurantee on the composition of store bought sand which makes problems - when they do occur - easier to analyze.