PH and substrate help

#1
I'm slowly getting my 125 going
this wknd i took everything out since it was setup for salt and disoconnected all the pvc and put new in wiht just the stuff i need for fresh. I didnt think it would take me toooooo long
but lets just say it took a whole day of cleaning it out entirely including scraping carefully the blue paint off the back, the 2 questions i have are these, it's going to be a cichlid(jacob friberg and im pretty sure a few frontosa ) so i need to get the ph up and i want to do it naturally if at all possible
in my 55 i use coral mixed in with the n atrual gravel and a little in the Wet/dry system about 10 pounds total to get my ph up to 7.8 and stable, my question is how many pounds of coral would i need in a 125g tank to get the ph to 7.8 atleast and stable ? I'm thinking about going with some natrual sand from home depot ? for substrate i heard that peacocks like that much better than gravel and i wanted it pure play sand nothing else mixed in it so that leaves one place for the crushed coral and that's the wet/dry now it is much much larger than the 55 wet dry setup i have but im not sure how much i could put in there, ifi had to guess i'd say 20ish pounds of crushed coral in some pantyhose, O and what color play sand shoudl i use ? whats the exact name of it at home depot ?
Thanks in advance for all the help !!
Kurt