Getting the PH up

#1
I have a new 55 gallon tank and im starting to worry about the Ph levels its still blueish but if i had to gues its about 7.2 or.4 at best !! and thats with 9 pounds of limestone mixed in the gravel about 6 pounds and 3 pounds in a old stocking from my girlfriend down in the bio balls for my wet dry system
i have 13 African cichlids
7 labido chromi and 4 peacocks and 2 from walmart that lookeed realllllllly nice color not sure what they are tho
ones orangeish and the other is blueish
I just  can't understand whats goin on in my 3 tanks one 5 one ten and now my new 55 thats a about 2 weeks old
fish seem preety happy in the 55 i'm pulling my hair out why its not super high and why my other tanks are hanging around 6.8 if im lucky its like a yellow ish clear color
my tap water is like 7.6 easy out of the tap
so im at a loss of words where the ph is going down
what do u guys use to keep it up and make it stay up
i only want natural stuff no buffer stuff i hear its junk

Rd