My kh is 8-9 and gh is 15. I have neon tetras and black neons in this water and they don't mind at all. I have had them for about a year in a non co2 tank with a ph of ~7.9. I moved them over to my co2 injected tank and they are doing fine. Same kh and gh, ph is ~6.9. The only plant that i've tried that couldn't grow in my water was a small piece of tonina belum that I got as a freebee. I have corkscrew vals, rotala indica, anacharis, anubias, alternanthera reineckii, amazon sword, some moss, and HC. They all grow very well. Good luck.