What was missed in the first posting was what you wanted??? Rocks are like anything else we put in the tank, they may be good or bad, depending on what we want to do. I hope you have done some more reading and found out a bit about PH, GH, and KH as they are important items. Not as important as sometimes stated but something to keep in mind. Rocks are not bad or good! Rocks do tend to change the tank, but that can be good. If you have low PH and KH, adding some rock is one way to start to change the tank. Too many people just think about what they want for their tank. You got a lot of advise with nobody asking what you want in YOUR tank!
Until I get really good at finding what fish want, I like to stay with the mainstream fish as they will adapt to almost any PH/GH/Kh that they find---if it is stable. About the worst thing to do to fish is try to change the water. The novice normally finds himself chasing numbers so that the fish never get used to anything and they then sicken and die. All the time the novice thinks he must not have gotten the right "magic" and keeps changing things.
Go with what you have and don't try to remake the wheel. Let the fish find a situation where they can adapt and they will be fine.
If those rocks are truly dolomite limestone, they are alkaline but even then they will only raise your PH slightly to maybe 7-6/7-8. Fish and plants will never notice the change.
Worry less= enjoy more?