I was going to delve into aquascaping for the first time and was wondering what we’re good stones or rocks to use that won’t raise my ph to much. I have hard chicago tap water that’s a ph around 7.8-8. I had what I think in my head to be some good ideas of valleys and maybe a land bridge over it. What rocks would be good to create that look of a canyon valley with a possible land bridge. I would like to keep cardinal tetras like I have now with some other South American fish but don’t want the ph to go to much higher. Thank you for any help!